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Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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jmwkk341
Novice
Jan 10, 2012, 11:26 AM
Post #1 of 11
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Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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I'm completely over-hauling the AC system on a:
1998
Chevrolet Cavalier Z24
2.4L
Mileage: 166,000 miles.
Background: The AC Compressor was on its way out so installed a new one and have replaced the Accumulator, Condenser, Evaporator Tube, Serpentine Belt and Belt Tenionser. I had no intention of bothering the Evaporator, but I butchered one of the aluminum evaporator line connections coming out of firewall that goes to the condenser.
I know that replacing the Evaporator is a big job that (presumably) involves alot of work removing instrument panels, etc.
I have not been able to find good step by step instructions on the web as to on how to replace the evaporator core, perhaps because it appears to require alot of work and effort to access the part in the first place.
This is my 1st post, so have mercy upon me. 
Would appreciate any help!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 10, 2012, 4:36 PM
Post #2 of 11
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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Instructions exist but I don't have specifics with step by step and at the age things may break doing the evap and it may not fit right as the original. Damage is done and too bad because depending on what was wrong with compressor you frequent aren't going to get that dang alloy stuff apart without damage to do the accumulator and yes most compressors will want a new one or give you a hard time for warranty.
If nobody here has the specifics AllData.com will for I think $27.50 but that is unlikely to tell you or discuss a poor fit and it's hard to say depending on any complications. Not to discourage you but A/C is not very DIY friendly without some comprehensive know how or your work so far may be all in waste.
1. What was wrong with the compressor?
2. Did it leave debris and how did you guess at how much oil to use?
That's just the tip of the iceberg and hope you bought a new compressor no a reman,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Jan 10, 2012, 4:52 PM
Post #3 of 11
(14790 views)
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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Remove or Disconnect
- Negative battery cable.
- Recover refrigerant.
- Drain cooling system.
- Raise vehicle.
- heater hoses from heater core.
- Evaporator fittings from the evaporator and discard O-ring seals.
- Moisture drain tube from HVAC module.
- Lower vehicle.
- Instrument panel and console.
- Heater outlet cover and heater core cover.
- There is a mounting screw located in a recess in the center of the cover.
- heater core mounting clamps and heater core.
- heater core shroud and evaporator core.
- There is a mounting screw located at the middle of the front of dash.
Install or Connect
- Evaporator.
Tighten
- Screws to 1 Nm (9 lb in) .
- heater core should heater core and heater core mounting clamp.
Tighten
- Screw to 1 Nm (9 lb in) .
- Heater core cover and heater outlet cover.
Tighten
- Screws to 1 Nm (9 lb in) .
- Instrument panel and console.
- Raise vehicle.
- Moisture drain tube to the HVAC module.
- Evaporator fittings to evaporator using new O-ring seals lubricated in clean 525 viscosity refrigerant oil.
Tighten
- Fittings to 24 Nm (18 lb ft) .
- heater hoses to heater core.
- Lower vehicle.
- Fill cooling system and check for leaks.
- Evacuate and charge the A/C system.
- Negative battery cable.
Tighten
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jmwkk341
Novice
Jan 10, 2012, 6:05 PM
Post #4 of 11
(14783 views)
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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Thanks, Tom.
The old compressor had been making a shrill, high pitched metal on metal grinding noise when the clutch was engaged. Also, there was a fair amount of shiny metal shavings around the compressor.
I was not able to drain ANY oil from the old compressor. Since I'm replacing all components (accumulator, condenser, evaporator and lines) with new ones, I believe the system will hold between 8-9 ounces. I put 3 ounces of PAG-150 into the compressor. I'll add the appropriate amounts of oil to the other components per the GM info that I have.
I've never performed any AC work before, so this is definetly a crash-course that I have the luxury of taking my time with since this is not a primary or even secondary means of transportation.
Thus far on this car, I have completely (and successfully) replaced the rear drum brakes, replaced the power steering pump & replaced the O2 sensors. Pretty routine work for most, but is work I've never done before. This is the first car I've had where totally botched self maintenance wont result in me being stranded w/o transportation.
Yes I bought a new AC Delco Compressor.
Thanks kindly for the reply.
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jmwkk341
Novice
Jan 10, 2012, 6:28 PM
Post #5 of 11
(14781 views)
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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Thanks, Hammer Time!!!
This undertaking looks daunting as hell.
Taking on this job should be good therapy for my anal-retentive OCD nature.
Not sure if I want to tackle this now or get back to rebuilding the carbs I have totally disassembled on my 1976 Yamaha XS650C.
I'm having to fight the urge to remove that new compressor I just bolted up and slapping on a $60 Bypass Pulley and avoid the entire AC quagmire until warmer weather approaches in a few months,
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Hammer Time
Ultimate Carjunky
/ Moderator
Jan 10, 2012, 6:41 PM
Post #6 of 11
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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You don't have to respond to posts separately. We all see every post.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 11, 2012, 2:19 AM
Post #7 of 11
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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jmwkk341:
Hammer just found the "daunting" task for you - way to go Hammer!
Quick read - sorry, I'm way behind. Evaps in a CCOT (clutch cycling orifice tube) system like this car are not usually a problem spot alone. As said the dang alloys are like welded after even less years.
No oil from old compressor could be normal the noise suggests it was trashed. Do your thing. Read charging procedures up top and I can or someone provide more if you are up to it like total system capacities or educated guesses for how much oil to use for what was replaced and it is guessing unless you start from completely flushed out empty. No dipstick for that and it's imperative to be close.
Even I own one that when the time comes for a compressor hope I can catch it before a meltdown and when much newer started putting PB on those just in case so evap wouldn't be involved!
Good luck. "Measure twice, Cut once" as they say
T
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jmwkk341
Novice
Jan 11, 2012, 7:10 AM
Post #8 of 11
(14743 views)
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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Thanks Tom. I appreciate the offer of help.
Going into this, I had absolutely NO intention of replacing the evaporator core due to its location. All connections came loose rather easily, but on that last disconnect I just did not take the care necessary to avoid twisting the damn tube coming out of the firewall. I should have used some PB Blaster and put a wrench on the hex connection to immobilize it while wrenching off the black nut on the AC Evap tube. 
BTW, I did have a local shop recover the R134a in the system prior to be tearing into it. Cost me $27.00.
I have come across a couple Youtube videos on removal of the Cavy's dash/instrument panels and so forth in order to access and replace the factory radio, so I'm hoping that footage will be of some help.
i do have some questions - I was not able to pour any oil out of the old Accumulator either. Is that unusual?
When I get to the point of charging the system, how (or) will the lower ambient temps (even in my garage) affect pressure readings and charging conditions as compared to performing this work in warm or hot weather?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 11, 2012, 7:41 AM
Post #9 of 11
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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OK - A chart and they can be totally wrong for a '98 Cavalier (say all engines) 24 ounces 134a and 9 oz. PAG 150 oil but that's from totally empty and I'm surprised that much. To get oil out of an accumulator drill a hole in the bottom but some is still held up for sure. Heat it if you wish for more. My guess is that plenty of oil settles in condenser but varies by car and designs.
General: When/if a component is replaced you add how much you could dump out plus a couple for a system with that oil capacity IMO and it is subject to opinion and what happened. A blowout from a rock thru condenser may blow a lot of oil out or any sudden loss.
Know that normally a plain vacuum pull and that's critical should not remove significant oil. If you don't have your own pump then rent one. Don't just count on a shop down the street as YOU want to see it hold steady and if good you can add thru high side into the vacuum engine off with liquid into that vacuum till it reads positive pressure so NO air gets in. Purge lines with a spit (just a spit) of new gas before hooking them up. Air is the enemy with its moisture.
Done (retired) from this but still check out stuff live if asked. Hasn't been that hot here in a couple years for that long and the extremes seem to bring out the weak links/leaks in system faster with the higher pressures.
Just to refresh and remind you once you have refrigerant and a gauge set or whatever you are using is to think hard what is pressure, what is known vacuum and what/where the pure gas is. Be fast but don't choke compressor when charging when all done if forcing compressor to run. Once some cooling at vents is happening the compressor should be getting some lube - critical.
Hang in there,
Tom
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jmwkk341
Novice
Jan 11, 2012, 7:57 AM
Post #10 of 11
(14736 views)
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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My new vacuum pump is a U.S. General Two Stage, 3 CFM, 1/3 HP unit that I bought from Harbor Freight.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 11, 2012, 8:01 AM
Post #11 of 11
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Re: Instructions on Replacing AC Evaporator Core on 98 Chevy Cavalier, Z24
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Great. Anything that can just pull a full vacuum is fine. Really expensive ones are just faster and those venturi ones can't pull the full 29.92 Hg at sea level adjust 1 Hg/1,000 ft. of elevation is ok
Tom
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