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How to: Add Air Conditioning to your CRX

Sat Feb 11, 2006 2:21 pm

I'm stuck in Chicago traffic at noon, or blasting down the highway trying to keep my hair in the car. A/C is no longer a luxury. So, on the hottest day of summer, I head to my local scrap yard to start stripping off the pieces I needed.

The summer of '99 was a [killer] for two weeks here in Northern Illinois. Normally, the sunroof will take care of it - or at least so I thought.

1st Mistake - Know ALL the items you'll need to take from your junked cars. This made one trip turn into 7.

2nd Mistake - Take a camera along to see how things are mounted and how they fit. You'll fumble around A LOT less later on. At least diagram where the parts came from, and what fasteners were used.

3rd Mistake - Always check if the systems are empty of freon. It's possible to flash freeze bare skin when you open up a charged tube and it sprays out. I ALMOST did that once.

Take a look at an online parts place like Majestic to see the diagrams of the parts you need.

New parts needed:
Desiccant can (dryer)
Ring gaskets (for R12 or R134)

At the salvage yard:

From the Engine compartment, start at the compressor and take EVERYTHING it connects to.

Compressor mount,
Toss out the desiccant can (but keep the rubber plug on the bottom and the aluminum spacer at its bolt point),
keep the switch,
Keep the ENTIRE wiring harness intact (every point can be disconnected instead of cut - normally) up to the piece that mounts on the firewall that has 2 vacuum hoses.
Keep the vacuum hoses connected to that piece and mark which end connects high and low on the throttle body. You will need the second diaphram on the trottle body, the one you don't have on your car (this is 1st gen specific, the ECU replaces this piece on the 2nd gens).
If the Condenser is still on the car (rarely), VERY CAREFULLY disconnect the tube and hoses. (otherwise go buy it from the yard office - make sure THEY remove the hoses first to make sure they're not seized tight) Take the 4 plug mount that the wiring harness plugs into.
Take the tubes all the way back to the firewall From inside the cockpit, (remove the glove compartment, you may have to detach the whole dashboard as well to get at everything.
Get the A/C switch of the environmental array. It pops out if you push it from behind with a thin screwdriver. It's also possible to wedge it out from the front - but you'll ding it up.
Get the evaporator from underneath the dashboard, it's black and left of the air blower. Take the silver hoop clamp from the blower as well.
Take the "Mitsuba" box off the wall next to the blower.
Disconnect the wiring harness from the blower and the connections under the carpeting.
That's it for the parts you need. I recommend keeping as many extra good fasteners as you can get, and take good notes as well. The biggest recurring problem I had was with Condenser fittings either seized solid or broken off. I went through 3 before I got a good one.

In your driveway:

You basically reverse the steps listed above. Start at the interior first and work your way forward. Though I've heard you can do this without loosening your dashboard, I personally don't believe it. Disconnect your speedometer cable if you have to do this by unclipping it from the tranny and feeding it through the firewall to give it slack.

Inside your interior:

Pop out the black tab (from the front) and pull out the blue electric plug. Plug it into the A/C Switch and "snap" it into the array.
Take off your glove compartment.
Take off the translucent pass though blower pipe. Give it to someone who's taking the A/C OFF their car (it happens).
Pull out the plug for the evaporator lines, pull out the plug for the carpeting and the condensed water tube as well.
You should find some unconnected wires in there as well. Connect these to the wire harness.
Wedge that #*^&$ bastard evaporator into the spot and loosely bolt it in. Make sure you put that hoop clamp on first! Tighten the clamp them tighten the mounting bolts.
Connect the wire harness to the blower.
Attach the Mitsuba box to the wall and connect it.

Inside your Engine bay:

Take this perfect moment and have your radiator serviced. Take it off and have a shop give it a good cleaning. It's MUCH easier to attach these parts with the radiator off! If you do it the HARD way (like me), try this while leaving the radiator on.
Attach the Compressor mount to the Engine block. You WILL have to re-tap these holes, as they are full of oil and road grime.
Attach the hoses to the compressor (both of them) and attach the compressor to the mount. (NOTE: if you're doing it the hard way, use a jack to raise it into position) You'll have to work the hoses around to get the thing in. Put your radiator back on if it was off.
String the wiring harness around the front of the car, attach the 4 plug mount, the radiator fan, the switch, the compressor, all the way around to the vacuum switch.
Mount the condenser and all tubing to evaporator, attach wire harness to motor. Attach vacuum switch to firewall and attach the vacuum hoses (they will be capped on the throttle body).

Take your car to the shop for R12, or DIY with R134 (NOTE: R134 uses a different set of ring gaskets, make sure you match the right sets!) I've also had great success with the R12 alternative called Duracool.

Let the rejoicing begin!

Sat Feb 11, 2006 8:46 pm

I've done this upgrade on my 91 CRX Si, and one extra added benefit of A/C is that you can de-fog your windows instantaneously with it in the winter.

Good writeup Paul. Was that on your 1st gen? It sounds almost identical to the 2nd gen A/C system.

Sun Feb 12, 2006 2:29 am

It was on my 1st gen, but i think honda put the AC kits together pretty much the same way for both.

Sun Feb 12, 2006 9:14 am

I missing a compressor myself. Whomever had mine before decided to rip the copressor out, and leave everything else in (evaporator, condenser) and ripped the suction line. The liquid line (the small one) looks like it's still intact.

I'm going to need AC, I live in the middle of florida! O.O

Mon Apr 21, 2008 12:24 pm

wow this would be more helpfull if you had pics...

Mon Apr 21, 2008 4:17 pm

gabe_si wrote:wow this would be more helpfull if you had pics...

so follow his instructions, take pictures, and post them up!


Mon Apr 21, 2008 4:39 pm

Ragnaarok wrote:
gabe_si wrote:wow this would be more helpfull if you had pics...

so follow his instructions, take pictures, and post them up!


there not so detailed...there good but not that good..

Mon Apr 21, 2008 5:35 pm

Pics? Here's a bunch of A/C related pics I've tossed on photobucket the years... Let me know if you want a pic of something in particular and I'll see what I can do.

Basic component locations and hard line routing:

Here's what you'll find under the dash of a non-A/C car, though this is viewed from above:

The big box is the evaporator - it replaces the middle duct in the above pic. The pair of lines immediately under it are the fluid lines (you only need one) that run from the evaporator to the front of the engine bay... They're marked yellow in my first pic. The two streight (well, one's bent) lines below those are the fluid lines that runs in front of the condensor. The big line on the left is the vapor line from the evaporator, marked light blue in my first pic. The remaining line on the right runs between the condensor and drier canister IIRC.

A different view, with the wiring harness and relays pointed out:

Yet another view, though this is of a Civic 4-door. The systems are nearly identical.

Sanden versus Matsushita compressors... The biggest give away is the size of the pulley:

A Duracool conversion kit and R-134 conversion fittings. The fill hose is junk - it started leaking from the joints the second time I tried to use it.

R-134 converted fittings:

Conversion fitting removed:

Tue Apr 22, 2008 9:38 am

i think my compressor is the mitsu kind cause it has a big pully

Wed Apr 23, 2008 8:20 am

good stuff...okay...i just need to know were the harness plugs in..cause i have alot of stuff hanging around...and i dont know what goes to what..i also have stuff thats cut...and i want to see how the condesor hooks on..cause i dont think i have room for it and the radiator..also do you know were the cables from the dash hook up to the control face..that controls the ac...i have 2 cables i bought used and i have been trying to figure out were they hook under the dash..

Wed Apr 23, 2008 8:46 am

gabe_si wrote:okay...i just need to know were the harness plugs in..cause i have alot of stuff hanging around...and i dont know what goes to what..i also have stuff thats cut.

The harness hooks up in a number of places. :)

- A 2 pin connector for the thermostat switch on the evaporator housing.
- A 6 or 8 pin connector that hooks up to the main wiring harness near the big firewall grommet.
- A 1 pin connector that plugs into the main fuse box on the engine bay side of the grommet.

After that, the harness makes a 2-3 foot run along the frame rail up to the passenger headlight area where you find:

- Two 4 pin relay connectors for the condensor fan and compressor clutch relays.
- A grounding ring for the relays
- A round 2 pin water-tight connector for the pressure switch down under the battery tray.

From there the harness snakes along under the main radiator fan shroud, up over the condenser fan shroud and attaches to a bracket on the far side. There, you should find:

- A 2 pin relay-like connector for the fan noise condenser.
- A 2 pin connector for the condenser fan motor.
- A single wire and bullet connector for the compressor clutch.

gabe_si wrote:and i want to see how the condesor hooks on..cause i dont think i have room for it and the radiator

Are you using a huge aftermarket radiator or some kind of custom radiator mount? The condenser mounts in front of the radiator, tucked in under the bar with the hood latch in it. I'm using a OEM-style dual-core replacement and the condenser fits just fine.
The bottom of the condenser has a couple of rubber bumper things that sit in a couple holes in the radiator support. The top has a pair of rubber mount things that bolt onto the front bulkhead (the big chunk of the body that the headlights bolt to) right below the bolts for the hood latch crossbar.
Here... I don't feel like taking my bumper off to illustrate, but you can see the top of the condenser through the hole for the safety catch:

gabe_si wrote:also do you know were the cables from the dash hook up to the control face..that controls the ac...i have 2 cables i bought used and i have been trying to figure out were they hook under the dash..

Didn't I answer this already? :)

Bottom of the air handler, looking up from the passenger foot well. Please excuse the rigged-up wiring.

In the engine bay, looking down between the firewall and air intake tube. The glared-out circle in the bottom middle of the image is a fuel pressure gauge screwed into the fuel filter.

Wed Apr 23, 2008 10:16 am

omg thanks for the cable pictures...damn i got the first one...but the one going through the firewall I would have never gotten...Thanks abunch...yea I have an aftermarket radiator looks like the 92-95 model ones..its small...as for the ac harness i just wanted to see pics of what hooks were...but regardless endless thanks for the pictures...IM thinking im just gonna get the cables in place and just pay a mechanic to hook up my ac.. See im in the process of rebuilding a crx and it had a load of probs..my ac face control is broken like most crx's so im rebuild that...and the harness for it was ripped...and im done rewireing and making it...all i needed to know was were the cables went...

Mon Jun 09, 2008 12:25 pm

Hmm. This is very helpful.

I have a 91 CRX HF, can I get A/C this way also? Or will this only work on an SI?

Also, at the scrapyard, what cars can you pull these parts from? Is there a list of all the interchangeable parts and all the cars that contain them somewhere?


Mon Jun 09, 2008 12:52 pm

Yes, you can install A/C in a '91 HF, any A/C system you pull out of an '88-91 CRX should fit just fine - just make sure it's been properly discharged before disconnecting any lines.

Most junkyards have big books of interchange information, though I doubt they'll cover individual hoses and lines. As far as I know, the major components like the evaporator, condensor, compressor and fan should be the same as the ones you find in '88-91 Civics, just make sure you're dealing with an OEM system... If it's aftermarket, all bets are off. The Civic wiring harness might be a little longer, but that's not really a problem. The hard lines might be different, which could be an issue - Aluminum doesn't like being bent and re-bent, so the hard lines really need to fit properly from the start.

Mon Jun 09, 2008 1:28 pm

One other question.

My CRX has the evaporator connections coming out of firewall into the engine area, but do you know of any other parts that would already be in the car? Or is it normal to have these connections just sitting there not connected to anything?

Mon Jun 09, 2008 1:48 pm

That means the car once had A/C, but someone removed most of the system. They probably skipped the evaporator because they didn't have the duct that's supposed to be installed in it's place. Does your heater control panel have an A/C button? Does your car have two radiator fans (really the radiator and condenser fans)? If so, does the driver's side fan switch on when the larger passenger side fan comes on (would indicate that at least part of the A/C wiring harness is still in place)?

Mon Jun 09, 2008 2:34 pm

I do have the A/C button on the heater control panel, but there is only one fan. Is there any other way to figure out what parts I might have or not.

I've got about 5 days off in a row coming up in a few days and I'm going to try to finish this by then because 2 weeks after that I'm going to South Carolina..

I was reading in the post that it might be best to take it to a shop to do the freon part of the A/C, is that true or can you just do it by your self?

Mon Jun 09, 2008 6:52 pm

dtyrrell88 wrote:Is there any other way to figure out what parts I might have or not.

Take a look at a diagram on one of the Honda parts sites... Go through your car and check off what you do and don't have.

dtyrrell88 wrote:I was reading in the post that it might be best to take it to a shop to do the freon part of the A/C, is that true or can you just do it by your self?

You need a vacuum pump to clear all the air and moisture out of the system and a manifold gauge set to connect the pump and then the refrigerant can tap to your A/C system. If you don't have access to either of those, it's probably cheaper to pay someone to take care of it than to buy the equipment yourself.

Mon Jun 09, 2008 11:37 pm

bobski wrote:Take a look at a diagram on one of the Honda parts sites... Go through your car and check off what you do and don't have.

Speaking of Honda parts sites.. Are there any that anyone knows of that are really good or specially tuned to CRX's?

Thanks for all the help.

Tue Jun 10, 2008 1:03 pm

Okay, here we go. I just took the initiative and took some photos of my own car. If anyone could help me identify any of the things in here that would be great.

These are the 2 hoses that I have sticking out of the firewall. I was researching, and I believe they are the to the evaporator, but I'm not sure if I have an evaporator, or what it looks like. v v v v v
Another photo of it v v v v v.


Here's the entire picture v v v v v v.

This, v v v v v v v, said A/C Serial No. and it had a number below. Does this mean that I did at one point have A/C? And, is this a component of the A/C?



This, v v v v v v, I am not sure about, but clearly it connects to that black box thing and goes through the firewall. I was thinking it was something with the evaporator maybe, but I'm not exactly sure what the evaporator is.



So, I'm not sure what some of these other pictures have that might be helpful, but I'll put them up anyway. I'm open to any ideas or comments, thanks.

Oh and sorry for the fuzzyness, and I think one is upside down.. :oops:

Tue Jun 10, 2008 1:09 pm

your car had AC at one point and yes, that is the evaporator

Tue Jun 10, 2008 2:17 pm

Wooo! Alright! Score one for me.

So, that thing under the dash on the passenger side is the evaporator. Where does that connect too? Because it seems like the evaporator hoses are coming through the firewall on the engine side of things, but not on the interior of the car, or are they different hoses?

Tue Jun 10, 2008 2:41 pm

The big black box under the dash with the serial number sticker on it is the evaporator. The connection on the bottom and hole in the firewall is supposed to be for a drain tube. Judging from the amount of grime in the A/C line connections, it's been disconnected for some time. It's not worth letting all that grit float around in your A/C - I would junk the evaporator and start from scratch. Well, scratch + the button. :)

A/C systems work like this: They take a gas, known as the refrigerant, and compress it... That is, run it through a pump which puts it under pressure.
When you compress a gas, it heats up. Temperature is sort of the amount of energy in a given space... The energy density if you will. If you compress a gas, jamming more matter into a smaller space, the matter will carry it's heat-energy through the process and you'll end up with more heat-energy in that particular space - A higher energy density, aka temperature. If you remember your high school science classes, this is what the gas laws were all about.
Anyway, the now pressurized, hot gas is then fed into a heat radiator. The excess heat-energy picked up during compression is released into the air outside the A/C system. As the refrigerant cools, it condenses into a pressurized liquid.
In our A/C systems, the pressurized liquid is then fed into a reservoir canister with a pouch of desiccant (water-absorbing material) in it. This isn't crucial to the operation of an A/C system, but it's good to know it's there. Refrigerant pours into the top of the canister, a tube picks it up from the bottom and feeds it to the remainder of the A/C system.
Ok, so the pressurized liquid runs from the drier canister through a tube across the front of the engine bay, along the passenger side to the firewall. Once inside the car, the fluid hits a restrictor valve. This valve limits how fast the fluid can flow past it, maintaining pressure between the compressor and the restrictor.
The down-stream side of the valve is low pressure - actually the same pressure as the gas at the beginning of it's trip. The sudden drop makes the fluid start to boil and evaporate. Since the pressure goes down, you get the opposite effect as you had going through the compressor... You have less matter and heat-energy in a given volume than you did before the valve, so the energy density (temperature) drops.
The liquid actually takes some time to pick up the heat-energy it needs to boil and convert back to a gas... To help it along, the low pressure liquid/gas mixture is fed through another heat exchanger. Air from the blower runs over the fins of the heat exchanger, passing heat-energy to the low pressure fluid/gas mixture inside, letting the fluid boil and cooling the air.
From there, the gas mixture runs back through the firewall, back to the front of the engine bay and into the compressor inlet, repeating the cycle.

So, the loop goes: Compressor, condenser, drier canister, expansion valve (part of the evaporator assembly), evaporator, compressor.
The only other parts you need to worry about are the various A/C lines in the engine bay, the wiring harness with relays and relay bracket, the second radiator fan, that drain tube and the firewall grommets (the big one for the A/C lines and wiring harness, and the little one for the drain tube).

Tue Jun 10, 2008 11:20 pm

But I also need the compressor and condenser, correct?

Wed Jun 11, 2008 8:47 am

- Compressor
- Compressor bracket with belt tensioner
- Compressor belt (get a new one, $10-15)
- Compressor inlet and discharge hoses
- Condenser
- Condenser fan
- Evaporator with drain hose and grommets
- Blower to evaporator and evaporator to air handler sealing straps
- Drier (get a new one, $30-40)
- A/C hard lines
a. bottom of the condenser to the drier inlet (kinda squiggly, silver)
b. drier outlet to cross-tube in front of the condenser (squiggly, black)
c. cross-tube in front of the condensor (black with elbows at each end)
d. long front to rear line (pressure switch near the front, service port near the back, silver with insulation)
e. long rear to front line (larger tube, service port near the back, silver with insulation)
f. misc hard line mounting brackets
- Complete A/C wiring harness with relays and relay mounting bracket
- O-rings for each and every A/C line connection (get new ones, $20 or so for a kit)
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