AC issues (1 Viewer)

[beachedwhale]

Recently replaced ac compressor, expansion valve, and condensor. i am having issues while the vehicle is parked and the ac is on and it doesnt blow cold air (5-10 degrees cooler than ambient). once i get moving it gets cold and if i drive for a few hours it starts getting warm again. my manifold gauges read 50 psi on the low side and 290 psi on the high side at 92 F. This is all at idle 700 ish rpm.

Thoughts?

 

[SHIfTHEAD]

Did you pull a vacuum when you changed all the parts? And have you hooked up gauges to the Hi and Low side while running? Sounds to me that the pressures are off which is either due to too little freon in the system or you didn't pull the vacuum prior to filling it.

 

[ramangain]

I think 50 on the low side is on the high side, if that makes sense.

 

[SHIfTHEAD]

Depending on the ambient temps these pressures will change.

https://www.acprocold.com/wp-content/uploads/2011/11/Temp-pressure-chart-33776F1.jpg

 

[Rebus Knebus]

Fan clutch?

 

[tg470]

High side AC is probably much too high. You should be checking high side with engine at around 1500rpm (not idle speed / 700 rpm). Typically ambient temps in the 80s/very low 90s will have a high side of 190-230.

Either overcharged or you aren't getting good enough airflow across the condenser. Assuming you pulled a proper vacuum, the sight glass will help you a lot. Spec is something like you should see foam within 10 seconds of compressor cycling off. If overcharged, sight glass will usually look clear for an extended period.

 

[flintknapper]

High side AC is probably much too high. You should be checking high side with engine at around 1500rpm (not idle speed / 700 rpm). Typically ambient temps in the 80s/very low 90s will have a high side of 190-230.

Either overcharged or you aren't getting good enough airflow across the condenser. Assuming you pulled a proper vacuum, the sight glass will help you a lot. Spec is something like you should see foam within 10 seconds of compressor cycling off. If overcharged, sight glass will usually look clear for an extended period.

^^^^^

Sight glass is next to worthless with the R134a system. A hold over from R12 days when it meant something.

Useful only if you are way out in BFE with no gauges and no other way to charge the system.

USE GAUGES to troubleshoot.

When starting with an evacuated system ALWAYS 'weigh in ' the refrigerant charge.

 

[beachedwhale]

Did you pull a vacuum when you changed all the parts? And have you hooked up gauges to the Hi and Low side while running? Sounds to me that the pressures are off which is either due to too little freon in the system or you didn't pull the vacuum prior to filling it.

yes pulled vacuum and let sit for 30 min and returned to the needle right where i left it. hooked up the r134a purged the line and then opened the low side valve.

 

[beachedwhale]

fan is running well.

 

[flintknapper]

yes pulled vacuum and let sit for 30 min and returned to the needle right where i left it. hooked up the r134a purged the line and then opened the low side valve.

30 minutes is enough to establish you have no leaks (or not significant ones) but is NOT enough time to pull a deep vacuum on the system (if you didn't continue to do so). How much total time did you vacuum the system and how much lubricating oil (PAG46) is in the system?

Also, what was the reason for the compressor replacement?

The reason it is important to pull a deep vacuum on the system for a decent period of time (not less than 1 hr., 2 hours preferred) is that it takes time to boil off and remove the moisture in the system. This is especially true if you don't have/use a good 2 stage vacuum pump and use NEW oil.

All too often folks use a rented unit from a Auto Parts store which is usually single stage, usually worn out or leaking and has either old or no oil in it. Not good.

 

[beachedwhale]

30 minutes is enough to establish you have no leaks (or not significant ones) but is NOT enough time to pull a deep vacuum on the system (if you didn't continue to do so). How much total time did you vacuum the system and how much lubricating oil (PAG46) is in the system?

Also, what was the reason for the compressor replacement?

The reason it is important to pull a deep vacuum on the system for a decent period of time (not less than 1 hr., 2 hours preferred) is that it takes time to boil off and remove the moisture in the system. This is especially true if you don't have/use a good 2 stage vacuum pump and use NEW oil.

All too often folks use a rented unit from a Auto Parts store which is usually single stage, usually worn out or leaking and has either old or no oil in it. Not good.

pulled vaccum for a total of 1 hour then let sit for 30 min. single stage pump from the ol' hazard fraud.

 

[flintknapper]

pulled vaccum for a total of 1 hour then let sit for 30 min. single stage pump from the ol' hazard fraud.

OK

Do you happen to remember how many inches Hg it registered on the gauge (vacuum). Just want to be sure we can eliminate any potential issues. Also...the amount of lubricating oil put back in the system? Thanks.

 

[flintknapper]

Recently replaced ac compressor, expansion valve, and condensor. i am having issues while the vehicle is parked and the ac is on and it doesnt blow cold air (5-10 degrees cooler than ambient). once i get moving it gets cold and if i drive for a few hours it starts getting warm again. my manifold gauges read 50 psi on the low side and 290 psi on the high side at 92 F. This is all at idle 700 ish rpm.

Thoughts?

If you don't mind, please post what year model your vehicle is and if it has rear air as well.

We like for folks to put the year model of their vehicle (and whether Land Cruiser or LX470) in their signature line, so we always know at a glance what we are dealing with.