a/c shutting off (1 Viewer)

[babyhydro]

Hey guy i have a 05 lexus that the a/c compressor shuts off after about 40 minutes, with the gauges on it the readings are normal but as the engine bay gets warmer the high side creeps up to 450 and the high pressure switch cuts the compressor off, First thing and obvious was the a/c clutch fan would keep spinning with the motor off, got to be it very common on all vehicels with same symtoms nope didnt fix it, so we move onto the drier figuring the bag was coming apart check it and indeed it was and did have some metal in it, replaced it same problem also with a denso compressor flushed system and retried same problem figured hell let do the expansion vale checked it spring was cocked so we figured now we got it same problem, we are stumped anybody have any similar issues ? truck milage is 200,000 approx

 

[OEMGUY0720]

Two things why this is happening:
- no more refrigerant, just top up and use a guage to do so (also check/observe for leaks)
- if it’s going high pressure (assuming ac refrigerant is adequate) it should be the evaporator not getting adequate cooling - may need to check your auxiliary fan

 

[babyhydro]

Two things why this is happening:
- no more refrigerant, just top up and use a guage to do so (also check/observe for leaks)
- if it’s going high pressure (assuming ac refrigerant is adequate) it should be the evaporator not getting adequate cooling - may need to check your auxiliary fan

New evaporater,charged with a machine and also charged with gauges and a 30 lb cylinder multiple times, No aux fan , 05 doesnt have one, and evap adequate cooling would not cause it as it made to absorb heat from the cabin, now condenser would be a different story

 

[OEMGUY0720]

New evaporater,charged with a machine and also charged with gauges and a 30 lb cylinder multiple times, No aux fan , 05 doesnt have one, and evap adequate cooling would not cause it as it made to absorb heat from the cabin, now condenser would be a different story

i stand corrected there thanks yes it is the condenser rather the evaporator.

 

[1972FJ55]

Three things I can think of that would cause those kinds of high-side pressure: 1) the outside of the condenser had mud or debris blocking airflow 2) the inside of the condenser is plugged with debris from the compressor 3) system is being overcharged.

 

[babyhydro]

Three things I can think of that would cause those kinds of high-side pressure: 1) the outside of the condenser had mud or debris blocking airflow 2) the inside of the condenser is plugged with debris from the compressor 3) system is being overcharged.

It would be I've replaced the condenser and compressor, compressor first, charged and evacuated more then 10 times with machine and old school way with gauges and tank, also I own a repair shop and have been doing a/c work for 35 years, but you never see everything

 

[white_lx]

It looks like you did the right things and you know what you are doing.

I can only add that these vehicles have rear A/C. If you had metal shavings in the system, there can be a lot of debris stuck in the rear A/C lines as well. You mentioned you flushed the lines, but that probably did not include the rear A/C system (with its own TXV). Did you have the rear A/C on while filling the system? It has a solenoid to control the rear TXV.

Also, it is not completely clear from your first post if you replaced the condenser. It could be partially plugged from the metal shavings you found in the system.

Any chance there is some moisture in the system that freezes and creates a blockage? Does the system equalize quickly (H and L) after the compressor switches off at over-pressure?

[Edit] Have you checked the temperatures of the refrigerant at condenser inlet and outlet? This way you can easily exclude the condenser as being a problem.