A/C Not Cool Enough

[Tim]

One of the risks you take when installing used air conditioning components is that they may be defective. That being said, I have a problem with some component(s).

The A/C is not cool enough. There are no refrigerant leaks, the pressure on both sides is correct, I have a working recevier drier, and no electrical problems. When the system was first pressurised, all was well. The low-pressure pipe used to condensate with moisture, and things behaved as they should. Now it seems that barely any cool air comes through the vents. The high pressure line is hot to the touch, and the low pressure line is somewhat cool but I'd say it's around 50 degrees or so. It's not enough to make it condensate or anything, like it should.

The system also makes a lot of hissing, which makes me wonder if I have a bad thermostatic expansion valve.

The compressor might be another possibility but I doubt it since the idle bogs down whenever the A/C is on.


Any thoughts or opinions?


Regards,

Tim

[mechanicaldj]

exactly what are the readings on your gauges? did you flush the system after installing used items? how long did you evacuate the system after the install and did you use a commercial grade vacuum pump? i hope the receiver/drier was brand new and not exposed to the elements for a long period of time.

[Tim]

exactly what are the readings on your gauges? did you flush the system after installing used items? how long did you evacuate the system after the install and did you use a commercial grade vacuum pump? i hope the receiver/drier was brand new and not exposed to the elements for a long period of time.

Don't quite remember the exact readings, but they were what the shop manual said. A week later I went back to have it topped off and the pressure hadn't changed.


I had the whole thing installed and sealed for about 2 wks before it was evacuated with a commercial grade vacuum pump, oiled and then charged.

The R/D, which had sat in the open for a week or 2 before installation, worked find except for one problem: The R/D was from a Nissan and somebody soldered the Festiva pipes on it, and it leaked.

That afternoon I pulled the R/D off of a sealed and still charged Festiva at the Junkyard and within 45 minutes of doing so it was connected to my system, evacuated, leak tested, oiled, and charged.

It did produce cold air - and to a certain extent still does.


Regards,

Tim

[mechanicaldj]

at 2000+ rpm, does the low side start dropping into a vacuum? - replace the thermostatic expansion valve(not with a used one!). is your source of R12 reliable and do you have a scale or recovery/charging machine? does the needle in your gauge fluctuate rapidly on your high side? - replace compressor. and which manual are you using?

[Tim]

I'll have to look into the pressure readings - I don't own the equipment I used for the A/C.

I do have a pretty reliable R-12 source, my mechanic has one of those charge/recover machines.

I followed the guidelines laid out in the Festiva factory shop manual when charging the system.


Regards,

Tim

[FB71]

not cool enough, huh? maybe get it a big gold chain.....

[Tim]

I was considering some Wal Mart spinning rims but violence against me and my car was threatened if I put them on...
:lol:


I guess my car is too cool for the community to handle! :lol:


Regards,

Tim

[mechanicaldj]

most likely you need a thermostatic expansion valve located inside the evaporator housing behind glovebox or the bulb(coil of aluminum tubing attached to the valve) has came loose from the low side tube of the evaporator( it is taped on by some ugly sticky tape) inside the evaporator housing. OR another likely cause would be contaminated refrigerant, either by air or other gases in your refrigerant, in which case you will need somebody that has a refrigerant identifier(costs between $300-$600)which can purge any air in the system and tell you what the composition of your refrigerant.

[mechanicaldj]

hey, also try a hundred freshener trees hanging from your rear view mirror so you can look cool and smell cool too! if that doesn't work, just become a ..............LUMBERJACK!!!!!!

[Tim]

Thanks!

TXVs only cost $20 new so it won't really set me back too much for a new one...

I've never taken apart the evaporator housing; can it be done while the system is still pressurised?

I'll add a note about this in my DIY air conditioning article once it's resolved.

Before I discharge the system and start replacing stuff, I want to be absolutely sure that the cause of insufficient cool air isn't something minor like a badly adjusted air vent door, loose bulb, or lack of condenser fan.



BTW, I have a hunk of cedar on a string that I'm going to put on my review mirror...


Regards,

Tim

[mechanicaldj]

the vent door should be obvious, if it doesn't blow through the center and side vents , that would of been your complaint, besides heat can't blow through those vents. now on the evaporator housing, I've always taken them out of the car before taking them apart. and to be absolutely positive, like i said previously, have someone do a refrigerant identifier check! WHOOPS! i forgot one thing: CHECK TO SEE IF THE RADIATOR FAN COMES ON SHORTLY AFTER THE A/C IS TURNED ON! AND ONE MORE THING: your engine doesn't run hot at all does it? and condenser fan is nice to have if you are running R-134a or any aftermarket freons.

[Tim]

I'll have the refrigerant ID'd next weekend.

The radiator fan comes on after a while. Not immediately but like 5 minutes later.

The temperature gauge has never gone past the 1/2 way mark. On a warm day it will be just a hair below 1/2. I replaced the thermostat a few months ago.

Regards,

Tim

[Tim]

I believe I've found the problem: the compressor. I went over to the mechanic's today and the system was still at normal pressure, but the pressure gauges didn't deflect or anything when the compressor's clutch was energised. Further supporting the defective compressor theory was that there were little drops of refrigerant oil on the bottom of it, indicating a leak.

Went to the junkyard again and selected a clean (not too greasy) specimen from a still pressurised system. I also learned that patience is a virtue when depressurising A/C lines. To make a long story short I let the gas escape for a while, and after about 2 minutes of this I got kind of impatient so I decided to speed things up and undid one of the lines leading to the engine compartment. Big mistake. I saw some foamy stuff come out of the pipe and then whoosh! Everything within 5 feet of the car was covered in refrigerant oil and some sudsy stuff.

By the way, would it be a good idea to replace the thermostatic expansion valve while I'm at it? I think the one in my car is still good but I don't know how to test it.

Regards,

Tim

[mechanicaldj]

Definitely a good idea to replace the Thermostatic valve at the same time for 2 reasons : #1 crap for the bad compressor could have traveled to it causing other problems down the road & #2 when you remove the evaporator housing and open it up (careful not to damage the other capillary tube, for the cycling switch, in the process) you will probably find crap in the intake side of your evaporator giving you reduced air flow over the core and after cleaning it, it will act like a brand new system, with a blower that you never knew before!

DO NOT FORGET TO CHANGE OUT THE OIL FROM THE NEW COMPRESSOR
AND PUT NEW OIL IN PLUS 1 to 2 OUNCES MORE FOR SH*TS AND GRINS!!

[Tim]

Thanks for the tips!

Is there any way I can leak test my new compressor before installing it so I don't spend $75 only to find it's got a problem, too?

On that note, how difficult is it to replace the seals in the compressor? Before the old one leaked it worked just fine and it'd be nice to have a backup.


Regards,

Tim