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Help diagnose 2000 T&C a/c

tscaravan on Sun March 31, 2013 1:31 AM User is offline

Year: 2000
Make: Chrysler
Model: Town&Country
Engine Size: 3.3
Refrigerant Type: 134
Ambient Temp: 50F
Country of Origin: United States

Hi guys, need a little help getting pointed in the right direction.

2000 Town&Country 3.3, first warm day of the season today (60F) and air doesn't blow cold. Quick check: compressor runs, outlet pipe of compressor gets hot, no pipes are frosted or even very cold to the touch. No signs of leaks anywhere (no oily/dirty spots at connections, etc.) Equalized pressure (engine off) about 55psi at about 50-55F ambient. Running at idle lo side about 20-25psi, hi side about 150-180psi. Pressures spread apart a bit more when cranking the throttle to 1000-1500rpm. When shut off, pressures equalize smoothly but quickly, about 20-30 seconds.

There is no cabin air filter and looking through the inspection opening behind the glove box, evap looks OK, no oily spots, nothing blocking it, nothing unusual. The a/c was not run since fall, but we do run the compressor all winter for defrost purposes.

Any idea where I might start looking? Many thanks.

NickD on Sun March 31, 2013 5:39 AM User is offline

Is this 50 or 60*F? I would look first for a 80*F day. Do you have automatic climate control?

GM Tech on Sun March 31, 2013 10:20 AM User is offline

And why do you think you have a problem? You are expecting ice cubes out the vents? at 60 degf ambient? It is not a refrigerator.... Auto a/c does not work that way- Like NickD says- wait for a warm day- and give it a test.

You'll go broke "looking" for problems that don't exist!

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

mk378 on Sun March 31, 2013 12:01 PM User is offline

I agree with GM Tech, testing in cool weather is at best inconclusive. You won't get condensation or frost if the dew point is below the temperature of the pipes (about 35 F).

tscaravan on Sun March 31, 2013 4:32 PM User is offline

Thanks guys, I'll give more info. It was 60F and sunny mid day, van gets hot inside under these conditions, dark and leather. Happens every year spring and fall. Wife drove car, reported AC blows air at outside temp, no cooling. She knows car well, has owned it for many years. I trust her observation as factual.

Van has manual A/C, front and rear. When I took pressure readings later in the day the ambient was down to roughly 53F.

I understand it's desirable to wait for warmer weather but when it gets to 80F the van will be unusable without A/C. I'm trying to avoid having to rent a car when that happens. Anything I can check out at the present (50 to 60F) ambient?

tscaravan on Sun March 31, 2013 4:40 PM User is offline

Quote
Originally posted by: mk378
You won't get condensation or frost if the dew point is below the temperature of the pipes (about 35 F).

I am absolutely certain none of the pipes were anywhere near 35F. They did not feel any colder than other metal parts on the car. I will try to take some temp readings on the pipes, but I only have an inexpensive IR gun that doesn't read accurately on reflective (aluminum) surfaces.

GM Tech on Sun March 31, 2013 5:42 PM User is offline

Number one failure mode in mobil a/c is loss of refrigerant- the only way to know if you've lost some due to a leak is to recover and weigh refrigerant.

Yeah it is hot in the greenhouse, but if evaporator has no hot air across it (outside ambient air) then the system won't do much- other than push the ambient air inside the cabin, which should suffice- personally, I'd crack the window a tad and enjoy the fresh air out the vents- and push the hot air out.

Do your same test with a known good factory refrigerant charge amount in the system.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

WyrTwister on Mon April 01, 2013 7:52 AM User is offlineView users profile

Was the compressor running ? Cycling ?

God bless
Wyr

tscaravan on Thu April 04, 2013 6:27 PM User is offline

Thanks guys. I do understand the importance of correct charge, I just want to pre-diagnose so I don't recover and recharge several times.

Today was warmer so I took more data:

OAT 63F, equalized pressure 50psi
At 1500rpm, pressures gradually increase to 20/250, then radiator fan kicks on, pressures decrease gradually to 5/120, fan goes off, repeat.
Compressor runs continuously, does not cycle
Compressor outlet pipe at 200F+, all other pipes and evap core at ambient temp.
Air comes out at dash outlets at ambient temp.
Temperatures measured, not guessed.
Blend door does work as it should.

Dougflas on Thu April 04, 2013 10:01 PM User is offline

Even if yout IR gun is a cheapie, it should be ok. If you shoot the front evap in and out, you're looking for a difference. The readings should be close to the same. The output should be slightly colder. I'm willing to bet that you're low on charge.

ice-n-tropics on Fri April 05, 2013 4:21 PM User is offline

Sooner or later most T&C leak at the lower passanger corner of the condenser.
hotrodac

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Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

tscaravan on Fri April 05, 2013 4:49 PM User is offline

Thanks ice. Is that corner of the condenser usually visible so I can check it with UV light?

AutoCool on Sat April 06, 2013 5:38 AM User is offline

You wrote that you have rear AC so don't forget to check the tubing and rear evap area for leaks.

Edited: Sat April 06, 2013 at 5:51 AM by AutoCool

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