AC Diagnosis Help

2014 Tacoma AC stopped blowing cold.

Compressor clutch works, engages and disengages as it should.

Hooked up manifold gauges to test pressure.

**Edit - Updated test after fixing issue with high side coupler pin**
- Ambient temp 65°F
- Low side static pressure 38 psi with engine off, high side same.
- With AC running after engine warmed up, low side -1.5 psi, high side 70 psi.
- After engine shutoff, low side 47 psi, high side 46.5 psi.

Seems I have low refrigerant level and possibly a leak?

 

I bet your gauge coupler isn't pushing the valve down in the fitting or your gauge is dead, it's almost impossible for one side to be at 0 psi if there's refrigerant in the system.

 

Thanks for the help. I'll try another gauge set. The coupler on this one does seem to be properly seated.

 

You were right, there was an issue with the pin in the coupler. Got it fixed and now have the proper readings. Will update OP with findings.

 

Going by the pressures it's low, static pressure on a fully charged system should be about equal to ambient temp.
Running at that temp I would expect to see 25-35 on the low side and around 150 ish on the high side.
Dye added to the system and a UV light finds most leaks but sometimes they can be difficult to find even with a "sniffer" tool.

 

A leak and also a bad low pressure switch. The compressor should cut out at ~20 psi.

 

There's no low pressure cycling switch on 2nd gen trucks, the high side combination pressure switch will turn off if the static pressure drops below around 30 psi but it won't cycle the compressor on low pressure.

 

Dammit, I knew that. CRS on my end.

Am I half right, low on freon?