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toyota truck questions on ac

macs_5 on Tue June 30, 2009 1:26 PM User is offline

Year: 88
Make: RN4
Model: 4x4
Engine Size: 22 RE
Refrigerant Type: converted 134

Okay, here goes,

88 toyota pickup lost cooling last summer, found leaks at the drier and recently at the evaporator, on the connections for the low press switch and expansion valve. (recently went thru that expansion valve fiasco, bought one from AMA and fits perfect). Replaced drier and used a partial can of r134 to pressure the system to check for leaks with TIF electronic leak detector. No leaks found, used soapy water to test all B-nut connections and no bubbles. ran both bubbles and TIF unit down lines and across condensor, no leaks found. Okay, purged 134A from system and started pulling vacuum with JB DV142. Reached 28 inches after about 45 minutes. Shut down vacuum and gauges have held same reading overnight. (had to go to work) This morning, gauges still holding and restarted vacuum to make sure I have a good evacuation.

Now comes the question; To my knowledge, the R12 oil was not drained from the system originally. Since then, the ac was working very well until it quit and that was due to the leak at the drier bottle. I am prepared to add 4 oz of ESTER Oil to the system to replace the oil depleted from the system due to the leak and removal/flush cleaning of the evaporator prior to installing the new expansion valve.

Question is: Is Ester oil still the choice for converted systems and does 4 oz/pressurized 2 oz cans achieve a fairly approximate addition? (I know the FAC book says to replace 0.7oz to evaporator and about the same to a drier and figure with the leak, that 4 oz is probably a good number). Of course, I could remove the compressor and physically drain it, but its kind of situated in a hard to get to location. So any additional pointers would be appreciated.



TRB on Tue June 30, 2009 2:15 PM User is offlineView users profile

I would use the BVA Auto Glow oil which s a POE. I would also try and remove as much of the mineral oil as you can!


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mk378 on Tue June 30, 2009 3:05 PM User is offline

You'll get better results removing the compressor and draining it. Any leftover mineral oil is useless in a R134a system, it just gets in the way of the refrigerant. My friend has a couple of those trucks and though I haven't actually tried (he actually prefers to drive with the windows open, so they sit empty), it looks like it would be pretty easy to take the skid plate off and drop it out the bottom.

Put in the full rated charge of ester oil since you're basically doing an oil change. Rather than pressurized cans buy a reputable grade of oil in bottles, open one of the lines, and pour it in.

macs_5 on Tue June 30, 2009 5:40 PM User is offline

well, I think I can probably figure on taking out the compressor. When charged with 4 ozs of ester and 1/3 can of R134, started cooling down to 81 degrees at center outlet. ambient outside was 94 degrees. after about 5 minutes at 2,000 rpm, lo side gauge hit 120 an hi side hit 325. Compressor kicked off, both guages equalized at 120 lbs.

So figuring that all things being normal, this would seem to indicate an internal compressor problem, leakage at slider or valves. Still no external leaks found. So what do you folks think? I should mention that the vacuum held at 28 for over eight hours and the pressure testing supports a tight exterior system. Well thanks for the replies so far and yea I know I can drop the skid plate, been there and done that when we overhauled the drive train. Have a great day, I am still out to lunch on if there is anymore possibilities, wish it was air in the system but that could only happen if something was internally blocked and holding a pocket of air which did not respond to the pump evacuation. Oh well, back to the drawing board.

By the way, anybody have any technical data on the ac amplifier? I have testing criteria, but FSM does not go into any great detail about its function and characteristics.

Thanks again.


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