A/C not cold

More info you may not want to know or may be you do.

Here's a story that happened to my 92 caddy (regular 4-door sedan) that may help you out:

About 2 yrs ago in mid summer, the ac in my Caddy started to go slowly but steadily - it would take longer and longer to cool dn the interior. After about a month later it quit completely - it would only blow hot air. The control panel would light up SERVICE A/C about 1 wk before it died completely. I took the car to a Caddy service center and they said the evaporator is clogged (a key part that sits inside the dash and condenses water from the air). The fix? - ~$1000, including parts and labor! I said forget it, pd the $50 diagnostics charges and went to a different shop (also a Caddy place) because I wanted the A/C fixed but for all I know for a ~$1000 you can get a brand new system put in! Guess what? - the other Caddy place knew after 15 mins the A/C was completely out of freon!!! (That was the gas used back then). For a total of $200 I got the leak fixed, A/C recharged with some ozone-friendly refrigerant and the SERVICE A/C light gone. The system does not work nearly as efficient as freon-based, only about 80% as efficient but it works great nonetheless - as well as it can on a non-freon refrigerant.

I wonder what some of the mechanics are doing at the service shops where labor rates are $100/hr and all they seem capable of is replacing the engine oil and perhaps the oil filter...

By the way, the efficiency of a freon-based A/C is incredible. I have experienced it. It's a pity it's bad for the environment.

Another btw: These days modern cars do not use any gas or liquid in the A/C - they use what's known as Peltiers' modules which is pure electronics to cool down the air (no leaks to worry about). I know Caddy's have had it for at least 8 years in their vehicles. But there are some car makers (and they are in the majority) who still don't use it.

-hth, me

Peter D. did pass the time by typing:

Actually the majority of new cars use R134a. Peltier junctions although neet to play with are also power hungry little monsters with limited heat sinking capacity. The upper limit is set by BTUs required to cool the vehicle.

Cadillac and Lexus use a peltier style seat-cooling/heating concept which I find quite interesting but I've never seen an automobile with pure electric cooling.

At any rate, here is some interesting reading

So, in other words, take it to a shop and have them check it out. Didn't know if there was any testing/looking I could do myself. If any of the parts are bad, they should still be under warranty. Less than 12 months old.. labor will have to come out of my pocket, though.

Eric did pass the time by typing:

You can do some basic checking.

Does the compressor run with the AC on. Does it cycle or run all the time.

If it's cycling put a hand on the inlet and outlet to the condenser (at the firewall) both should be very cold to the touch. (if this is the case you have enough gas)

If one is cold and the other warmer by about 10deg then you could be low. Checking requires a pressure gauge on the low side.

If it runs all the time you might be low on gas. Then you just have to get a pressure gauge for the type of refrigerant used in the system and follow the directions.

If it cycles properly then you may have a vac leak where there is just enough vac to operate the doors when your at idle but not enough under acceleration or driving. I suspect this option since you talk about good AC at idle.

What doors are you talking about? By the way, this is in a 99 TJ (and the system uses R134, I'm sure). I'll do as much of that checking as I can.

As usual, thanks again Doug!!

Eric

DougW did pass the time by typing:

Erm.. I blame the Scotch for that..

Should have said Evaporator... the condenser is in front of your radiator. :)

Oh well, at least it's good Scotch.

Eric did pass the time by typing:

There are doors (valves) in the AC system that change how much air goes past the coil and how much goes past the heater core (called a blend door) as well as a set of doors that determine what goes where (floor, bi, vent, defrost, etc) These mostly run on vacuum (or mechanical linkages in older models). If there isn't enough vac (leak in the system somewhere or disconnected line) they tend to stay shut. It's hard to say for sure without the service book or knowing what you have in there.

If it is a leak it can be anywhere. Check to see if it cycles properly first then press with looking for leaks. A big vac leak will also cause a rough idle condition.