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86 Nissan

AS on Sun August 12, 2007 12:35 AM User is offline

Year: 1986
Make: Nissan
Model: D21 Pickup
Engine Size: 2.4L
Refrigerant Type: R134a
Ambient Temp: 104
Pressure Low: 72
Pressure High: 250
Country of Origin: United States

I'm converting my 1986 Nissan D21 pickup to R134a. Changed the receiver/drier, blew air through evaporator, condenser, put POE in old compressor. When charging it starts out taking the R134a quickly, but soon slows down quite a bit. Can only get a little over a can (12 oz) in it. Discharge hose from compressor is very hot, and I can feel a pulse in the line. Lines on each side of drier are hot, suction line to compressor is warm. Air blows about 80 degrees. When I turn A/C off, pressure goes to about 150 on high side and low side pegs (at 120). Do I have a bad expansion valve? Bad compressor?

Chick on Sun August 12, 2007 6:04 AM User is offlineView users profile

Did you pull a deep vacuum?? Did you change into the vaccum, allowing the vacuum to pull in as much as it could?? Do you have good airflow over the condenser? Lastly, why did you convert to R134a? Did you have a leak, or just cooling issues??

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

AS on Sun August 12, 2007 11:41 AM User is offline

The A/C stopped working a couple of years ago--no R12 in the system. There was a leak at one of the service valves and one of the hoses. Replaced hoses and valve cores. I pulled a vacuum--let the pump run about 45 minutes. My guage has a pretty small scale but it looked like it was about 28-29 inches. I closed both valves on the guage manifold, attached R134a can, purged the service line to the manifold and opened up the low side valve to let the refrigerant into the system, then started the truck and turned on the A/C.

AS on Sun August 12, 2007 11:43 AM User is offline

Forgot to mention I pulled the condenser and cleaned it--was really dirty, and set up a fan in front of it while I was charging.

mk378 on Sun August 12, 2007 12:21 PM User is offline

It really acts like there's air in it, but pressures can be high with high ambient like that. If engine driven fan, the fan clutch is probably shot leading to such a high high side. Fans in front of the car don't do a lot. You could try spraying water on the condenser to cool it.

But really the problem is the low side is too high, thus it can't pull refrigerant out of the can. Either the compressor is tired or the expansion valve stuck open. Did you take any of the old mineral oil out or just pour in more POE, may have too much oil as well.

AS on Sun August 12, 2007 2:19 PM User is offline

I drained the old oil from the compressor, and blew air through the condenser and evaporator. Didn't get much oil from either of those. I didn't take the evaporator out--just blew through the lines from the engine compartment--would that be a problem since I was blowing through the expansion valve? I wouldn't be surprised if the compressor is tired--after all it's a 1986 truck. I'll check the fan clutch and track down the expansion valve, although I suspect a rebuilt compressor is in my future. Would I need to change the drier again if I replace the compressor? There hasn't been any metal or other crud in any of the oil I got out. I appreciate your help.

AS on Wed August 15, 2007 3:19 AM User is offline

We have cool air! Replaced the expansion valve and compressor and with a little coaxing from a spray bottle got a decent charge. We won't be making popsicles, but it sure makes it livable again. Thanks for all the advice.

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