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85 Dodge Pickup, Double checking cooling

knkreb on Mon June 23, 2008 5:59 AM User is offline

Year: 85
Make: Dodge
Model: 1/2 Pickup
Refrigerant Type: R12
Ambient Temp: 85
Pressure Low: 30

Just finished up a new install of a compressor in an old truck. New compressor, TXV, receiver. The old compressor worked, it just had a leaking shaft seal. Pulled good vacuum down to 1000 micron. Recharged to factory specified charge.

New compressor pumps fine. At idle it has 30 psi suction. 55°F Suction Temp, Discharge air temp is 58-60° (at idle) Estimated about 175-200 psi head pressure (didn't have a 5/16 fitting available) Estimated by taking mid point temperature on condensor and converted over to R12 saturated temp. Looking around 10~° Subcooling. The system looks like it's doing it's thing by all parameters, but it just doesn't seem like the temperature drop is really there. For the short trip that was taken on the road, it went down to 57°F Discharge air temp. I've only ever really messed around with GM R-12 systems before, and from what I remember about them was they were very cold on the discharge air temperature. This system is running about 57-60° Discharge air temp. I would rev up the engine, and the suction pressure would drop to about 15 psi, suction temp didn't start to drop any more.

Am I just expecting too much here or what?

You must have all the clues for an accurate diagonsis.

Edited: Mon June 23, 2008 at 6:02 AM by knkreb

Chick on Mon June 23, 2008 7:00 AM User is offlineView users profile

Does the system have a sight glass? make sure it's full, could be a little low. You do need the high side pressures, adaptors are available thru the sites sponsor if you can't get one locally. Once you can monitor the high side, you may be able to add a few more ounces, since you did lose some some in the charging hose/manifold. Could be as much as two or three ounces. Is the fan clutch in top shape? And are you sure you have virgin R12?? Let us know

Email: Chick


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