Automotive Air Conditioning Information Forum (Archives)

Tulenkot on Mon August 10, 2015 7:34 PM

Year: 2004
Make: Nissan
Model: Frontier
Engine Size: 3.3

2004 Nissan frontier 3.3 91k miles. So all of a sudden, I noticed a buzzing when the AC clutch is engaged, it fluctuates with rpm and is noticeable in the cabin, behind the glovebox area, but not really under the hood. At the same time the AC makes cool air but not as cold as it's supposed to. My fear is a bad compressor, but there is no bearing noise so I'm not sure what to think. I can spin the compressor with my hand with the engine off and is seems fine, no noises. Anybody ever have this problem?
With an AC manifold gauge I determined that the Low side is to high (55-60) and the high side is low normal to slightly low (155-160). I sprayed the condenser with water and the pressure readings became more abnormal, low - 60psi, high - 125psi. Any ideas now? I am still worried it might be the compressor because of the readings, but I'd think they would be closer together if it was a failure.

GM Tech on Mon August 10, 2015 9:13 PM

Sounds more like your TXV has lost control- and even vibrating- it alone could cause the abnormal pressures- and it is mounted right before the evaporator- so put your wooden stick on the liquid line as it goes into the firewall and see if you can feel it there......

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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......

Tulenkot on Mon August 10, 2015 9:17 PM

It's funny you say that, because the low pressure line is vibrating along the firewall. Just to clarify, TXV is the expansion valve, yes?

Dougflas on Mon August 10, 2015 9:37 PM

Correct, TXV is expansion valve. If you can remove the sensing bulb, place it in ice water ad then hold it in your hand. You should see a difference in pressures. Ice water will make it close down.

Tulenkot on Mon August 10, 2015 9:50 PM

Thanks guys. Big help. I'll post what I figure out tomorrow.

Tulenkot on Tue August 11, 2015 2:54 PM

Nissan says it's the compressor. I asked them why and they said it's not the TXV because they tested it so it has to be the compressor. What do you think?

GM Tech on Tue August 11, 2015 8:47 PM

I test the compressor by either pinching off a high side rubber hose (downstream from high side port) to see if pressure can go up to 400 or so. Or if nowhere to pinch, I intentionally overcharge to see if pump can generate high head pressure. If it can, then, it is NOT the compressor.....

-------------------------
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......

ice-n-tropics on Wed August 12, 2015 3:40 PM

Chrysler had a recall on rear txv for buzz caused by txv valve stem high rpm due to off center machining quality
Fix was a Fuji Koki txv
hotrodac

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Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
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