Need a diagnoses on my A/C

[xanis]

The air conditioning in my '00 Chevy Cavalier has been broken since last May. Being the cheapskate (or poor college student) that I am, I elected not to get it fixed. Well, it was a brutal summer and I decided that I couldn't take another without some A/C. I took my car to a repair shop to get the system checked for leaks and possibly get the refrigerant refilled. The mechanic put dye through the system and found no leaks. He put 15 pounds of refrigerant in my system. The whole thing cost me $90.

However, that didn't exactly do the trick. I tested it out yesterday since the weather was warm and found out that it wasn't blowing any cold air... in fact, the air coming out of the vents was warmer than the air outside.

So my question is this: If there are no leaks, and the refrigerant level is full, what else could be wrong? More importantly, whatever is wrong, how much am I probably going to have to shell out for this?

 

[iamwiz82]

15lbs? I hope you meant 1.5lbs or 15oz.

I'd say if that much was put in there is a leak. You can buy leak kits at the local auto parts store and it's easy to check. Plus you get a cool pen blacklight and yellow safety glasses out of the thing.

 

[alkemyst]

is the compressor coming on?

 

[bruceb]

First that mechanic has no idea of what he is doing. No way that car hold 15 Lbs of R-134A
more likely a maximum of 1.5 to 2 Lbs at most in new cars. If your system does not cool,
first look to see if the Clutch on the compressor is engaged. If not, the system needs to
be troubleshot by an experienced & certified ac service tech. It can be anything from a bad
Pressure switch, which can shut the compressor Off if pressures are too low or to high
to problems from the ac control head not telling the system to engage .. on gm cars, this
usually goes thru the computer system. It is also possible the compressor has failed
internally and would need to be replaced. Air in the system would also cause it not to cool also.
A plugged orifice tube will also cause it not to work. When in Vent Mode, are you getting
Engine Heat out of the Vents ? ? If so, it can be that the actuators that change from Hot to
Cold are not moving, therefore not shutting off the flow of hot engine coolant into the
passenger heater core.

 

[slickvic000]

It sounds to me like you have a blend-door problem. If the air blowing out of the ducts is warmer than the outside air, then this points to something that is putting a heat-load on the air your blower is blowing. If your compressor clutch does in fact engage, and stays engaged for a long period of time this would tell you that your high side pressure and low-side pressures are within boundaries and are not kicking the a/c compressor off. I have seen in a lot of newer vehicles the coolant flowing through the heater core does not include a coolant control valve, so the heater core will always be as hot as the engine coolant temperature. The air your blower motor blows always blows air first through the evaporator then through the heater core, if the blend door is set to let some air be heated. When no heat is desired, the blend-door will completely close off any air passage to the heat core and the air will only pass through the evaporator. Therefore if your blend door is stuck, or the actuator is not working, the air may be constantly heated from the heater core.

If this is in fact the case, the repair may be pretty costly since your whole heater/a/c assembly is behind the glove compartment and usually requires most of the dashboard to be taken off. If it is just stuck the technician may be able to lubricate it to free it up, or if an actuator is broken it may need to be replaced.

 

[alkemyst]

a/c work isn't that hard. These are a couple great videos:

Part 1

Part II

The clutch isn't covered in the above really. To test the clutch you want to check ohms on the clutch itself and it should be between 3-5 ohms, you should also have continuity.

If your don't the clutch is bad.

Now sometimes the clutch just burns out, sometimes it's caused by the front shaft seal on the compressor getting blowby or flat out leaking.

I am getting ready to replace the compressor on my wife's saturn this weeked.

a can of PAG, couple bottles of r134a, (have a gauge), o-ring kit, compressor, dryer, expansion valve (not really needed, but required for the warranty on the compressor ), and a few hours of my time. $480 vs $1050 at the shop.

Of course if you don't have the tools already and know how to use them it's a moot point.

 

[xanis]

First, I made a typo with the amount of refrigerant... it was 1.5lbs so I apologize for the confusion. Second, I appreciate all of the help and advice. Just about everything you guys have told me is way over my head seeing as the most I know how to do is change my oil/filter and check fluid levels. I'm going to see what the guy at the shop says when I get it looked at Monday. If the bill is too high I'm going to make some calls and see if anyone I know can do it on the cheap. If not.. then I think I might be going without A/C again this summer.

 

[boomerang]

If he couldn't find the leak then it most likely is leaking from the evaporator, which is inside the car. It can be difficult to detect leaks there because it's buried in the dash area.

Remember, it all leaked out before, there is a leak.

If he finds the evaporator to be leaking he should credit you the amount you've already paid. In my opinion.

 

[bruceb]

alkemyst ... since you are replacing a compressor, you need not worry about epa regs
as to releasing freon, as it already gone. However, when a compressor fails, it is a must
to flush out the refrigerant lines so none of the possible metal from the compressor internals
is in there. If it is, it will wreck the new one in short order. You also should change out the
Receiver Drier and the Oriffice Tube if you car has one, as that will be plugged with debris.
Also, when a system has been opened to the air, it needs to be pulled down with a Vacuum Pump
for at least 30 mins to get the air out. That also checks for leaks. No drop in vacumm & you should
be ok for leakage. Then you put in the refrigerant, which with R-134A is done in Lbs & Oz and needs
to be very close to what the label on the car says. If it is overfull, it will not work correctly.

I myself have taken and got my AC Certifications for both EPA 608 & 609 types of systems.

 

[alkemyst]

Originally posted by: bruceb
alkemyst ... since you are replacing a compressor, you need not worry about epa regs
as to releasing freon, as it already gone. However, when a compressor fails, it is a must
to flush out the refrigerant lines so none of the possible metal from the compressor internals
is in there. If it is, it will wreck the new one in short order. You also should change out the
Receiver Drier and the Oriffice Tube if you car has one, as that will be plugged with debris.
Also, when a system has been opened to the air, it needs to be pulled down with a Vacuum Pump
for at least 30 mins to get the air out. That also checks for leaks. No drop in vacumm & you should
be ok for leakage. Then you put in the refrigerant, which with R-134A is done in Lbs & Oz and needs
to be very close to what the label on the car says. If it is overfull, it will not work correctly.

I myself have taken and got my AC Certifications for both EPA 608 & 609 types of systems.

my system is still charged. I am replacing my compressor because the car is at 100k and the clutch died.

I already stated I am doing the dryer, and expansion valve (which I could just clean but the compressor company won't honor that for the warranty). I do plan to take it to a shop once it's back together so they can vacuum it and recharge. I can do the recharge part myself, but it's packaged with the job around here.

 

[Iron Woode]

My 1987 Crown Vic's air wasn't working when I bought it back '98.

I had it leak checked and there were numerous small leaks at various couplings. So I changed the o-rings to the new green ones. I then found a bad hose and replaced that (got a great deal on it at the dealership).

After rechecking the system, there was still a leak. It was the evaporator. I then decided to replace it and convert the car over to R134a. This was an expensive repair. I had to replace the accumulator/dryer as well as the fixed orifice tube. I didn't know that the accumulator/dryer was routine maintenance item, to be changed every 30,000 miles on my car.

The AC works great now.

My system holds 3.5 lbs of R12.

 

[bruceb]

Please let the shop install the new compressor. Since your AC is still fully charged
per EPA Section 609 regs, the refrigerant can not be vented to the atmosphere
and must be recovered. The shop will have a recovery machine to remove it from
your car in compliance with EPA rules. Penalties, if someone catches you, are very stiff.

 

[alkemyst]

it's R134a, are you sure you are an a/c tech?

 

[bruceb]

Absolutely ... I have my certifications for both EPA 609 (auto AC)
and EPA 608 type 1 which cover home AC units .. You can not
buy freon, especially for home units without the certifications.

No venting of R134 after Nov 1995 .. at this however, a non certified
tech can still buy R134 but not R12 .. only certified techs can get that.
All types of freon should be recovered to be in full compliance with
EPA regulations. You can read the EPA rules for Motor Vehicle AC here:

http://www.epa.gov/spdpublc/title6/609/justfax.html

 

[Pacfanweb]

Why do you need a new compressor if only your clutch is bad? Just replace the clutch and pulley. You don't even need to break the system open to do that. Might even come as an assembly with the field coil, too.
If the compressor is fine other than the clutch, I wouldn't touch it.

 

[bruceb]

I agree with with Pacfanweb .. if you can just change the clutch.
You will need special tools to remove and install it and on some
cars, it can be done with the compressor still mounted in the car.
Again, the a/c service shop will already have the tools. And a clutch
will be like 1/3 the cost of the whole compressor.

 

[alkemyst]

looks still proposed that law against R134a...still the job is done the a/c guys in my area told me it wasn't a problem (not that they are the brightest tools, I called 6 different shops and got the same answer...vent it then replace the parts and bring it in for the vacuum).

Job took about 3 hours then about 1 hour once I ran up to the a/c shop to have it vacuumed and recharged.

A compressor with 100k miles on it, more than likely has some shaft leak...this will eventually foul the new clutch and also progress.

Spending $200 on a job you will have to redo anyway vs $500 on having it last another 100k is a no brainer.

 

[exdeath]

Just to add something that hasn't been mentioned yet. The temp/pressure sensor near the evaporator under the dash that triggers the compressor intervals. This is what works in conjunction with the dial in your dash when selecting how cold the AC is and keeps the refrigerant at just the right temp/pressure by pulsing the compressor at timed intervals, so if that sensor isn't working it may think it's already freezing and not ever trigger the compressor to come on.

 

[bruceb]

You did not read the link at the EPA site ... it is a law that is currently in effect.
Apparently the so called certified techs in your area, need to take a refresher
course and start to get into compliance with EPA Clean Air Regulations

Handling HFC-134a
Venting HFC-134a Refrigerant

Section 608 of the Clean Air Act prohibits releasing HFC-134a into the atmosphere. The prohibition on venting HFC-134a has been in effect since November 1995.
Section 609 Regulatory History

In March, 1996, EPA proposed a rule to require recycling of HFC-134a. The rule proposed standards for recover-only and recover/recycle equipment and rules for training and testing technicians to handle this equipment. EPA requested comments from the public about this proposed rule, and, after reviewing the comments, published a final rule on December 30, 1997. This final rule will become effective on January 29, 1998. For more information about this rule, see the fact sheet " Summary of Final Rule Governing Substitutes for CFC-12 Refrigerant in Motor Vehicle Air Conditioners" available through the Hotline and the web site.
Approved Equipment

Technicians who repair or service HFC-134a MVACs must recover the refrigerant and either recycle it on-site, or send it off-site to a reclamation facility so that it may be purified according to ARI Standard 700. Technicians must use EPA-approved equipment to perform the refrigerant recovery and recycling. Recover/ recycle equipment cleans the refrigerant so that oil, air and moisture contaminants reach acceptably low levels. A list of approved recover/recycle and recover-only equipment is available from the Hotline and the web site listed above. Note that certain EPA-approved models can recycle both CFC-12 and HFC-134a refrigerants.