Ac problem

[DNP]

I have a 1994 buick lesabre with dual climate control digital.The ac system is in good shape.But i have to take battery cables off witch resets the computor.This will reingage the ac pump.It does not last.If it sits over night same problem.Anybody know whats the problem? No check engine light car runs great.No power to the pump wiwth out removeing the battery cables and resetting computor.?

[maxwedge]

Low or no freon is one possibility, also if the temp is below 40 the compresor will not come on,

[imidazol97]

Originally Posted by DNP

I have a 1994 buick lesabre with dual climate control digital.The ac system is in good shape.But i have to take battery cables off witch resets the computor.This will reingage the ac pump.It does not last.If it sits over night same problem.Anybody know whats the problem? No check engine light car runs great.No power to the pump wiwth out removeing the battery cables and resetting computor.?

When you start the car, does the temp readout start flashing for 90 seconds? That means the unit has detected a fault. I believe 1994 cars can NOT read out the error on the AC unit; it requires a TECH II type reader.

The most common fault is low freon pressure. My car has a 1995 unit in it (it's a 1998). The programmer has always turned on the error flash during cold weather. Unit operates fine. I just replaced the programmer because of the problem with the vacuum line connector in the corner of the box and I did something wrong testing the box, so I got a new replacement at a local wrecking yard.

The AC compressor is turned off below 50 deg or so. I believe that's based on the temperature ambient reading for the HVAC unit. Today it was 12 for the low here and the high is 26. You're not going to get to test your unit for a while.

Does yours still have the low pressure switch in the line close to the accumulator on the firewall? When it's warmer, you might bypass that switch to be sure that it is telling the unit there's enough freon. And has the freon been recharged? I assume that is R134a...

[imidazol97]

Originally Posted by DNP

I have a 1994 buick lesabre with dual climate control digital.The ac system is in good shape.But i have to take battery cables off witch resets the computor.This will reingage the ac pump.It does not last.If it sits over night same problem.Anybody know whats the problem? No check engine light car runs great.No power to the pump wiwth out removeing the battery cables and resetting computor.?

When you start the car, does the temp readout start flashing for 90 seconds? That means the unit has detected a fault. I believe 1994 cars can NOT read out the error on the AC unit; it requires a TECH II type reader.

The most common fault is low freon pressure. My car has a 1995 unit in it (it's a 1998). The programmer has always turned on the error flash during cold weather. Unit operates fine. I just replaced the programmer because of the problem with the vacuum line connector in the corner of the box and I did something wrong testing the box, so I got a new replacement at a local wrecking yard.

The AC compressor is turned off below 50 deg or so. I believe that's based on the temperature ambient reading for the HVAC unit. Today it was 12 for the low here and the high is 26. You're not going to get to test your unit for a while.

Does yours still have the low pressure switch in the line close to the accumulator on the firewall? When it's warmer, you might bypass that switch to be sure that it is telling the unit there's enough freon. And has the freon been recharged? I assume that is R134a...

[danielsatur]

Information perpose!
I have seen two tools, one would hook into the DLC ,and other into a cigar lighter to back feed 12volts to the system while relacing the battery.

Have you ever seen a Heat-pump for a house turn on in the winter time, when it's frozen?

[DNP]

Thanks for the repleys.This what i found today.The exterior temp guage would not come up with the car in heat for a couple of hours.So i went and bought a exterior temp switch and replaced it .Same thing no change have to pull battery cables to reset it than it will read correct.ac will work intill you drive it and get below 38 degrees.Than same thing .So i went to a freind that has the antaizeing equipment and he hook if up and tested the ecm and the havc control .He said the system is fine.He says the car has smart logic in the controler and the exterior temp guage wont chage intill its going down the road and the temp outside has to be above 38 f.For the ac to kick on.Also he says the exterior temp will change in a heated garage but it migt take a day. The car new it was not moveing.So it apears that i have been trying to fix some thats not broke .It took me several days to fiqure this one out.Thanks again

[maxwedge]

Air moving over the temp sensor is the only reason it is only accurate when moving, heat from the rad. area sitting still would skew the temp inputs.