A/C Compressor problem
08-09-2018
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A/C Compressor problem
New to the forum, hope I find some help. I recently replaced my compressor, condenser, and expansion valve on my 2008 Civic. Everything went fairly smoothly, until I tried to charge the system. I successfully took it down to -30 psi vacuum and it held for an hour. Had a pump on it for over an air to remove any moisture. Charged it, but the compressor will not kick on. Checked/replaced the relay, still nothing. Any tips on how to trouble shoot a brand new compressor that will not kick on? Thanks
08-18-2018
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Ok...finally got back to it. It was the 7.5 amp fuse in the engine compartment. Only thing is, now the ac does not cycle. The clutch remains engaged until the ac is turned off.
08-19-2018
#3
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Re: A/C Compressor problem
Crap, I now remember seeing your post one day last week but it dropped off my main page before I got to it.
If you tried to DIY charge it up without being able to run the compressor, I bet it's still low.
Both radiator fans run? Spin the correct direction?
Full blast blower fan speed, check:
What are the system pressures while running? At idle RPM? At 2000 RPM?
What is the ambient temperature? What color is the car and is the car sitting in direct sun?
Does the AC ever actually get cold enough for the system to cycle the compressor off?
How about at night when it's cooler outside? How about on LOW fan speed?
If you tried to DIY charge it up without being able to run the compressor, I bet it's still low.
Both radiator fans run? Spin the correct direction?
Full blast blower fan speed, check:
What are the system pressures while running? At idle RPM? At 2000 RPM?
What is the ambient temperature? What color is the car and is the car sitting in direct sun?
Does the AC ever actually get cold enough for the system to cycle the compressor off?
How about at night when it's cooler outside? How about on LOW fan speed?
08-19-2018
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high side and low side pressures are within range. I will test during cooler times. As I understand it, the compressor will cycle off during times of higher demand. When I took it out for a spin, it seemed to lack power until I turned the ac off.
Is it a cabin thermistor or would it be the evaporator thermistor that would signal the compressor to cycle?
Is it a cabin thermistor or would it be the evaporator thermistor that would signal the compressor to cycle?
08-19-2018
#5
If you think a good mechanic is expensive, try hiring a bad one
Re: A/C Compressor problem
high side and low side pressures are within range.
I use those numbers and other data to help judge what's happening inside an AC system as it's operating.
Does your AC actually cool? Adequately?
Got RECIRC on? (or max)
What's the dash vent temps? Is it cold on one side but not so cold on the other?
As I understand it, the compressor will cycle off during times of higher demand.
If thermal load is high it may not cycle off.
The system should cycle the compressor off when the evaporator core temp is just above freezing, typical turn off/turn on points might be around 35-39 degrees.
Dash vent temps won't necessarily be that low.
If it keeps the AC compressor running until the core freezes into a big ice cube, that's a problem.
08-19-2018
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When I say normal range, I was looking at a chart taking in consideration ambient temp. I believe low side was 45 and high side was 155.
Cooling very well. Coming out ice cold on all vents. Recirc was on.
Cooling very well. Coming out ice cold on all vents. Recirc was on.
Last edited by munson5501; 08-19-2018 at 12:16 PM.
08-19-2018
#8
If you think a good mechanic is expensive, try hiring a bad one
Re: A/C Compressor problem
Oh okay, yes the PCM can shut off the compressor depending on throttle position (and possibly the rate of throttle increase).There is also a service bulletin about this part being too sensitive resulting in complaints of poor AC cooling during hard acceleration from low speed such as in stop and go traffic.
Lower fan speed should make it more likely to cycle, if the evap core temp is really low enough to do so.
If it's literally ice cold and you don't ever see it cycle, stick a thermometer in the center vents and make sure it's not dropping into freezing range..
If it's blowing air out at 50 and never gets lower then it might be undercharged (155 seems a bit low but I don't have enough other data to judge it)
I have several digital meat thermometers from the walmart kitchen section I use for AC work. They are pretty quick to react, I can watch vent temps rise and fall those few degrees as the system cycles the compressor repeatedly.
If it's literally ice cold and you don't ever see it cycle, stick a thermometer in the center vents and make sure it's not dropping into freezing range..
If it's blowing air out at 50 and never gets lower then it might be undercharged (155 seems a bit low but I don't have enough other data to judge it)
I have several digital meat thermometers from the walmart kitchen section I use for AC work. They are pretty quick to react, I can watch vent temps rise and fall those few degrees as the system cycles the compressor repeatedly.
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