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No High / Low Side Pressure

turkeylurkey on Sun February 07, 2016 8:47 PM User is offline

Year: 2001
Make: Infiniti
Model: G20
Engine Size: 1.8
Refrigerant Type: 134a
Ambient Temp: 80
Pressure Low: 0
Pressure High: 0
Country of Origin: United States

Hi Everyone,

New to the forum.

Vehicle was in a front end accident, however, A/C still blew cold air for several weeks afterwards. Weather cooled down and I didn't use the A/C for a few weeks, then I went to turn on the A/C and it no longer blew cold air.

Thought the accident might have caused a slow leak, but I wanted to check 1st things 1st. I noticed the compressor was not turning on, checked the relay and swapped it out. Compressor still didn't turn on, so I jumped the relay and clutch / compressor engaged. Took the following readings:

Vehicle off:
Low: 0 PSI
High: 0 PSI

Vehicle on, with A/C relay jumped:
Low: -20 PSI
High 5 to 20 PSI

I tried to add refrigerant but the can doesn't seem to empty. When trying to add refrigerant, I notice a florescent green (color of Antifreeze) / oil mixture coming from the AC compress where the lines attach, that wasn't leaking beforehand. Odd since the refrigerant I'm adding uses a Red dye (not green).

Thoughts? Is the compressor shot?

GM Tech on Mon February 08, 2016 9:24 AM User is offline

You have a massive leak- the green color is the OEM dye that came with your car- it is in th eoil that remains in the system after the refrigerant leaked out.- and it is leaking right at where you see it-- you will need to fix that joint- possibly a crack in the manifold, or in the compressor- only you can decide that by removing the manifold and looking at the sealing surfaces. You will need to pull an adequate vacuum after joint is fixed and then recharge......

Most likely the accident bumped that joint and caused the crack......check it out.

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Edited: Mon February 08, 2016 at 9:27 AM by GM Tech

mk378 on Mon February 08, 2016 12:09 PM User is offline

Any time there is a leak down to zero, air will get in, you need to use a vacuum pump to remove it before charging. Of course you also need to fix the leak first. If the pressure is zero you can go ahead and take the connection apart-- look for physical damage, corrosion or maybe it is just a bad o-ring. Clean up all the dye and test with a small amount of refrigerant, just get the pressure up to 20-30 psi and leave it for a day (do not run the compressor at any point in this process). If the pressure holds then you can evacuate and charge properly; take it to a shop if you don't have a vacuum pump.

Don't use red dye. UV dye is the only type that is approved as fully compatible to use in a 134a system. Since UV dye is already present you don't need to add any. UV dye is what you saw, the same colorant that is in green antifreeze, it (and antifreeze) lights up really bright yellow under UV light.

Edited: Mon February 08, 2016 at 12:16 PM by mk378

turkeylurkey on Mon February 08, 2016 3:18 PM User is offline

Thanks guys.

I will perform a further inspection on the area that I see the leak and see what needs to be repaired. Massive leak seems odd since the A/C worked for a few weeks after the accident.

In the meantime, any thoughts on why the compressor is not turning on w/o jumping the relay? Is this due to there being no pressure / refrigerant in the system?

mk378 on Mon February 08, 2016 6:17 PM User is offline

It is possible this leak is a new problem not related to the crash. Things can break at any time.

Yes there is a always a pressure switch or sensor. It is to protect the compressor in case of leak-out. You should not bypass it and try to run the compressor with no refrigerant. Leave everything plugged in as stock. The compressor should start working again by itself once evacuated and recharged.

turkeylurkey on Sun February 14, 2016 1:17 PM User is offline

Thanks guys! That seemed to do the trick.

I disconnected the high pressure line that was seeping oil / dye and replaced the oring. I put a little PAG oil in the line (maybe .5 oz.?) the hooked everything back up. I then vacuumed / evacuated the system and refilled with refrigerant.

Once refrigerant was in the system, the compressor turned on as it should and the vents had cold air!


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