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Help diagnosing AC on fire engine

mhfd112 on Thu July 21, 2011 10:00 AM User is offline

Engine Size: Big
Refrigerant Type: R134a
Pressure Low: 78
Pressure High: 165
Country of Origin: United States

The AC in this truck is not performing very well. Sometimes it will put out pretty cold air, but most of the time it is pretty warm. Compressor doesn't cycle.

Thanks for your help.

mhfd112 on Thu July 21, 2011 10:16 AM User is offline

Getting ready to weigh the freon. Will post results shortly.

mhfd112 on Thu July 21, 2011 10:56 AM User is offline

System had 5lbs 4.75 oz. Tag on compressor says system charge approximately 5 to 6 lbs.

mhfd112 on Thu July 21, 2011 11:08 AM User is offline

Evaporator air filter has fell out and the evaporator is filthy. Could this be the problem?

bohica2xo on Thu July 21, 2011 11:16 AM User is offline

Typically a plugged up air side in the evaporator will cause low pressures, because it is not moving much heat.

It appears you have a correct charge of refrigerant.

What does the condensor look like? How does it get airflow?

Is this a TXV system? What compressor does it have?

With a correct charge in the system, those pressures look like a worn out compressor - or a badly slipping belt at idle.

What are the pressures @ 1500 engine rpm?


B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhfd112 on Thu July 21, 2011 11:29 AM User is offline

Condenser is clean and fins are in good shape. It is mounted in front of the radiator.

Compressor says ICE (International Components Engineering).

It doesn't have an orifice tube. It has what I would call an expansion block or valve.

mhfd112 on Thu July 21, 2011 11:56 AM User is offline

Think I found the problem. Took lines of at the expansion valve and the is a bunch of round balls plugging the line. I'm guessing a busted desiccant in the dryer.

mk378 on Thu July 21, 2011 12:13 PM User is offline

Is it a (improperly) converted system?

mhfd112 on Thu July 21, 2011 1:38 PM User is offline

It is a 2003 model. Factory R134a system.

bohica2xo on Thu July 21, 2011 1:52 PM User is offline

Sounds like you have a York style compressor. Have a look at the oil in the sump.

Dessicant bags fail sometimes.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhfd112 on Thu July 21, 2011 3:12 PM User is offline

I changed the drier and cleaned the evaporator. Pulling a vacuum now.

Oil in sump is about 3/4 up the site glass. Looks a little dark, but not terrible.

mhfd112 on Thu July 21, 2011 3:24 PM User is offline

Also blew shop air through the line between the drier and expansion valve to clear the blockage.

mhfd112 on Thu July 21, 2011 6:47 PM User is offline

Working better than it was, but still not as good as it did several years ago.

mhfd112 on Thu July 21, 2011 6:47 PM User is offline

Working better than it was, but still not as good as it did several years ago.

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