Model: S10 pickup 4x4
Engine Size: 4.3
Refrigerant Type: R-12
Ambient Temp: 87
Pressure Low: 26-30
Pressure High: 185
Country of Origin: United States
170,000 miles. My system is all stock. It's keeping me cool when on max but, the vent temp is still only 60. This is true at idle and on the highway. During my trip home from work last night (which is only 20 minutes) I left my vent thermometer in and kept an eye on it. It really never dropped below 60. It's been like this for awhile but, it kept me cool and I didn't have a high side adapter. I now have one so, I hooked up my gauges this morning. The low side was 38 at idle. Doors open. High was 185. I don't have a tach so I had to guestimate RPM. I believe I'm reasonably close to the 1500-2000 range. The low side then fell to around 26 at which time the clutch kicks out and pressure goes back above 40 or so then cycles again. This repeats. At idle the clutch will stay running as the low side stays high enough that the low pressure cycling switch is satisfied.
My thinking is, I'm a little low on refrigerant but, I thought I'd get the experts opinion. I's really rather not have it all taken out and redone because R-12 as you know, is expensive and hard to obtain. I do have a 12 oz can on hand. Should I add it? Thanks for your help? By the way, I got my tools from AMA including the Mastercool gauge set.
I just went and felt the evap inlet and the top of the accumulator. Both felt cold. The Evap felt a bit colder than the accumulator.
I had an '84 S-10 with A/C that I bought used around '88. While ice cubes never dropped from the vents, I stayed cool enough. Around '02, the A/C quit, and I took it to a local shop along with a couple cans of R12, and asked them to fix it. Man! Their repair froze me out! The technician told me he did not replace anything. But while recharging, he didn't like the pressures his gauges indicated. In his words, he "backwashed" which, he felt, washed out crud that was affecting cooling. I have no idea what he did.
The A/C quit again the next season. But I didn't have it looked at because the truck was subsequently traded for something big enough to haul two small children in car seats & me.
You're most likely slightly low on refrigerant. At an ambient of 90*, the system should not cycle. How fast are you cycling?
Called my kid's 93 SUV a hot box, all black, even the manual said 60 PSI low side was normal at 1,500 rpm in a 90*F environment with that CCOT system and an R-4 compressor, so tended to charge it on the low side to a more of a 55 psi to get under 60*F vent temperatures. And this thing always built up a lot of debris between the condenser and radiator. Reducing the high temperature low side pressure also results in increased cycling at the lower ambients. Cure for that was to shut down the AC.
Having 60*F air blast on you was far more comfortable than carrying 65 pound of rocks in a knapsack in 100+*F 25 mile forced march when I was in Texas. That didn't kill me either, but my kid wanted to use my Caddy, even though he wouldn't normally be caught dead in it on cooler days. Just saying, these systems were poor from the factory, but those 90*F plus days are rare around here, a couple of weeks in the summer, and only mid day, so lived with that for over ten years. But the heater was okay for those -30*F days.
He purchased a 2010 Nitro in a practically black color, sucker sure heats up quick in the sun. Rode with him last Friday, was okay when we left his garage, but was parked outside during our present heat wave. He commented will never buy a dark vehicle again, ha, I thought you said that when you got rid of that S-10. But just think, in a few hours will be dark, can take a cold shower and get in between cold sheets in my air conditioned home. We are only suppose to hit 83*F today.
So bottom line.....
Should I add freon or not?
Yes, add refrigerant. A few oz at a time. Wait a few minutes for the system to equalize. When you get the in and out tubes of the evap the same temp, add a few more oz.
At this point, do you think it will hold the whole 12 oz can?
I would not just put 12 oz in at once. Use 2 or 3 oz at a time.
I should have asked, what vent temp could I realistically expect from this truck? It's still at 60 this season with the fan on hi and using the Max setting. This keeps me from burning up but, I can't help but think it can be better.
We're in a heat wave right now so that makes me want a little more. I may add a little more freon but, I just thought maybe somebody can say what a reasonable vent temp would be for this old vehicle?
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