1988 F-150 Refrigerant/oil capacity R-134

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I'm going to be doing a full A/C system replacement on the truck in my signature. Compressor, evaporator, condenser the whole thing. This will be the first major A/C work I've done and I've got all the tools lined up. The compressor I have is a NOS motorcraft and has mineral oil in it, so I'll have to pour out that and replace with PAG 46. I know the original specs were 52oz of R12 and 10 oz of mineral oil. Last time compressor/condenser was replaced they used 40oz of R-134 and 10oz of PAG 46. Does this sound right? Also do you just put all the oil in the compressor or should I put some in the condenser and evaporator when I install?
 
I have the same basic truck. 85% of the r12 charge is 44oz.oil amount is ok. Change the orifice to an orange one...its roughly 15% smaller than the R12 one and the orange one really helps these trucks cool. Put the oil wherever you can fit it.

I assume your flushing all the old oil out? Spend extra time on back flushing the condenser.

May want to replace the fan clutch with a new us motorworks one,not a hayden.
 
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Yes
Originally Posted By: Chris142
I have the same basic truck. 85% of the r12 charge is 44oz.oil amount is ok. Change the orifice to an orange one...its roughly 15% smaller than the R12 one and the orange one really helps these trucks cool. Put the oil wherever you can fit it.

I assume your flushing all the old oil out? Spend extra time on back flushing the condenser.

May want to replace the fan clutch with a new us motorworks one,not a hayden.


Ok that sounds good on the capacity. I'm assuming I can just pour out the mineral oil that is in my new compressor without any extra flushing? I'm installing new condenser so not going to need to flush that. Interesting note on the orange orifice tube. I think blue was stock, and I was planning on going back with red which is in between the blue and orange.
 
Originally Posted By: E150GT
I hope you got a parallel flow condenser and not an old style tube and fin
if he did then the capacity will be much smaller. These trucks work great with the stock condenser.
 
Know this is an old post but figured I'd try updating this one before I did a new one.. So today ( I know only 11 months later..) I finally changed the compressor. I ended up just flushing condenser and evaporator (orange orifice tube) and installing a new dryer. Added the right amount of oil and was charging it up (after it held a vacuum overnight) after about the first can I noticed the connector on my manifold gauges was leaking a bit on the high side, tightened it up and continued filling. Added the correct 44 oz and my vent temps are in the mid/high 50's.. Not great. Its 85 degrees outside right now and my pressures are 33/150. Did a lot of my first can just get blown out? Feel like the pressures are to low for the temp, but I don't want to overcharge the system. What should I do next?
 
You can and should run with 100% of the specified R-12 amount in R-134a, unless the high side starts going too high. Which it is not.
 
You are low on R-134a (unless your ambient temperature is under 65). Pull up a chart of R-134a pressures vs ambient temperatures on the Internet and put enough more in to get to the proper pressure readings at your ambient temperature. You won't be overcharged if you watch your pressures. On a converted system, the precise amount of R-134a you use is less important then your pressures.
 
Well went to play with it today and right after I started the truck and it was showing 33/185 suction line/accumulator very cold, I just let it sit there and run for maybe 20min and after it had been running pressures went up to 44/295.. which is to high on the high side and the suction line/accumulator was still cool but noticeably warmer. Not sure what this means.. Ambient temps 90 degrees. I didn't add any freon from yesterday.

Would a bad fan clutch cause the pressures to keep rising like that? One on the truck is original. No over heating issues though.
 
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Yes it is likely a bad fan clutch. Put water on the condenser and watch for pressure to drop and cooling improve.

Fan shrouds and air blocks between the radiator and condenser must be in place. It takes a lot more airflow for good A/C performance than it does just to keep engine from overheating.
 
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