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740 Service R12 or convert to R134-a

What is the weight that you put in?

What is the weight specification on the sticker under the hood?
 
What is the weight that you put in?

What is the weight specification on the sticker under the hood?

I put in approximately 12oz (equivalent to 36oz of r134). I think spec might be like 42oz? (Equivalent to 14oz of ES12A). So I might be 2oz snort assuming I got ALL of the old Freon out. I didn?t know if that would be enough to make the compressor do weird things.
 
You still need to put a vacuum pump on it. To get all the old junk out of it and see if it holds with no leaks. you might be ok, Whats your gauges telling you?
 
You still need to put a vacuum pump on it. To get all the old junk out of it and see if it holds with no leaks. you might be ok, Whats your gauges telling you?

I did that already after I replaced the receiver drier. I simply went bybweight of Freon rather than gauge readings since I can?t get a high side reading. I returned the manifold gauge set to AutoZone already. Essentially i just want to know if it?s normal for the compressor to run all the time with this stuff. Am I in danger?
 
I’ll try to get a manifold set soon and base it just off of the cold side. What pressure should I be looking for with the compressor OFF around 80F, and how about on?
 
About 80 to 100 psi static and then about 30 psi when the compressor is on.

Does the high side get warm/hot to the touch and the low side get cold.
 
About 80 to 100 psi static and then about 30 psi when the compressor is on.

Does the high side get warm/hot to the touch and the low side get cold.

Haven?t checked. Away from the car now. I?ll check pressures later this week and add/remove if necessary.
 
Just noticed a few minutes ago that her AC quality kind of sucked at idle, but would get colder when revved to 1500 rpm. She then said it was much colder while driving. I got out and saw her pusher fan spinning so I don't think this is an airflow issue. I believe this is indicative of being low on refrigerant.
 
Sounds like a low charge to me. R12 capacity is 40 ounces. Converted to R134 would be about 32-35 ounces. With ES12, your charge should be 13-15 ounces.

Charge Chart
Temp Chart

That also reeks of weak compressor.

:nod:
Fear not, try adding some more refrigerant and see how it does. If it doesn't improve, I would start looking for a new compressor. Could also potentially be a partially clogged expansion valve.
 
Without pressure guages.....guesswork.

I just did a r134 charge on my 1990 240 and I blasted 2lbs into my system. I went by 85% of the weight posted on my r12 sticker.
 
I’m gonna add a bit more later this week.

I bought an expansion valve but didn’t replace it because I had no idea where it was located, and I didn’t want to open the system in too many places since I had a limited amount of orings on hand.
 
I?m gonna add a bit more later this week.

I bought an expansion valve but didn?t replace it because I had no idea where it was located, and I didn?t want to open the system in too many places since I had a limited amount of orings on hand.

Its in behind the passenger footwell, below the glove box.
 
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