AC is hot, low side pressure ok??? | Ford Explorer Forums - Serious Explorations

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AC is hot, low side pressure ok???

wes_99ebx

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CA
Year, Model & Trim Level
99 Eddie Bauer 5.0 V8
I've searched the forum for a couple days, but I'm not sure what to do. Apologies if this has been covered already.

My AC blows warm, but everything else works. I got an AC pro kit, and measured the low side pressure, which was only slightly low. I filled it, rechecked, and nothing. Waited a couple days, came back and checked. Still nothing.

At 65˚F, the low side pressure was 30 psi, which is what it should be according to the cheapo gauge. I believe I located the compressor clutch, and it was not engaged when set to Max AC.

The AC pro kit doesn't come equipped to check the high side pressure, and I don't have a manifold gauge, so I haven't checked that side.

Should I force the clutch to engage manually? I'd like to fix this myself if at all possible.
 



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30 psi static (system not running) is way to low. The compressor won't even engage at that pressure. You need to put more refrigerant in, the compressor will start to cycle. The 30 psi (pressure vs temp) should be when the compressor is running. Static should be up near 70 or more, depending on ambient temperature.
 






It is better to have the reading for the high side. Otherwise you are risking putting too much in there.
 






Pressures Equalize

Hi Wes,
When the compressor is not engaged the system pressures will equalize, both sides will show the same. With your system @ 30 psi as others have said your refrigerant is too low to turn on the pressure cycling switch which will supply power to the compressor. Add refrigerant until you get the compressor to kick on then look at your gage and see what you have.

If you compressor needs to engage to get the refrigerant in you can always jumper the plug on the cycling switch at the accumulator/ receiver/ drier.
Mike
 






Should I be worried about over charging the system? The gauge said that's what my pressure should be at at the current ambient temp.
 






Add refrigerant until the compressor engages. Then monitor your reading. If you are still too low the compressor will cycle very quickly until it gets a proper amount in the system.
 






So as long as the compressor isn't engaged, im not in danger of overcharging?
 






It can be overcharged if the compressor is not engaging. Jump the pressure cycling switch to get it going, after adding some re-plug the cycling switch back in, check your pressure frequently to see how much has been installed.
 






I added freon til the low pressure side got to around 50psi, and the compressor clutch kicked on for about 2.5 seconds. As it did, the pressure dropped to around 30, then when the clutch went off, the pressure rose agin to 50, and the cycle continued. Could this mean I have a leak?
 






It looks like that you are still low at the freon. Once the compressor is engaged, it should read 40 to 50 psi if outside temperature is about 80F. You do have a leak somewhere in the system which is the reason why you are low at the freon.

My A/C has the same behavior. Normally I put in two cans of R134A in later June and it last about 4 months until A/C is no longer needed. I have been doing this for the last two years and I plan to find the leak early next year. It could be the accumulator which is still original - 98.
 






Success! The compressor started to engage, then shut off after 2 seconds, and start after 6 sec, so I kept adding freon, and now it's about 7 seconds on, 6 seconds off. I thought this was a problem, but my AC is cold now, so I figured it was fine. Thanks everyone for the help.
 






That good to know. You need to keep an eye on how quickly the Freon will leak and also try to find the source of the leak and fix it. That is my next step also.
 






That good to know. You need to keep an eye on how quickly the Freon will leak and also try to find the source of the leak and fix it. That is my next step also.

Are there any tricks for locating a leak? I checked both high and low side pressure port caps, they seem good and tight. I know you can use smoke to locate a vacuum pump leak, and soapy water to find a bike tire leak, but I doubt either of those would be good for the system. I think I can smell the freon whenever I hit the gas pretty hard, and the AC shuts off anytime i get around 3500rpms (I think) Thoughts?
 






Did you know the pressure on both high and low side? When you say 'AC shut off' do you mean you don't get AC but compressor is still running or the compressor is disengaged when you hit 3500rpm?
 






Where to look for leaks

When there is a refrigerant leak it can also carry oil with it. Adding dye to the system will help locate some leaks with a black light. If it has been leaking for a while it will collect dust and dirt in that area making it visible. The areas easiest to locate are, compressor seals, "O" ring connections, and condenser leaks. If you have an evaporator leak you will need a sniffer to reach up into the heater box to tell.
Mike
 






Like radman says, you can sometimes see the oil from the leak. Trace out your A/C system from the compressor and you can follow the lines as they go through the system. Google a typical auto A/C system so you will recognize the components like the condenser, evaporator, dryer, ... Get a good flashlight and look carefully as you go through the system. You can see where the connections are made and you can look for leaks (oil) there but hoses can also leak at their factory made fittings and you have to replace the hoses if they are leaking.
 






Did you know the pressure on both high and low side? When you say 'AC shut off' do you mean you don't get AC but compressor is still running or the compressor is disengaged when you hit 3500rpm?

I mean I don't get ac, not sure if the compressor is engaged or not
 






When there is a refrigerant leak it can also carry oil with it. Adding dye to the system will help locate some leaks with a black light. If it has been leaking for a while it will collect dust and dirt in that area making it visible. The areas easiest to locate are, compressor seals, "O" ring connections, and condenser leaks. If you have an evaporator leak you will need a sniffer to reach up into the heater box to tell. Mike

Thanks!
 






Like radman says, you can sometimes see the oil from the leak. Trace out your A/C system from the compressor and you can follow the lines as they go through the system. Google a typical auto A/C system so you will recognize the components like the condenser, evaporator, dryer, ... Get a good flashlight and look carefully as you go through the system. You can see where the connections are made and you can look for leaks (oil) there but hoses can also leak at their factory made fittings and you have to replace the hoses if they are leaking.

Will do, thanks!
 



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