Not Cool!

[Danielle]

So glad to hear it whew!

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[79jasper]

I was just checking mine on the way home. I'm getting 50°F.
For a first time noob recharge, without changing the orifice or flushing it, I'd say I did okay. Lol
Don't have the heater core bypass either, and I run a 205° thermostat, so lots of heat in there.

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[gnathv]

Your 30 yr old compressor is running 400 on the high side. The compressor is fine.
I think you're overcharged, it is better than rolling down window, but it isn't right.
Low side should be around 40, high side 2 x ambient temperature plus about 20.
These are ball park, depends on temp and air across condenser. My 93 is converted to 134 and is
as cold as my 97, I used a variable orifice tube and it made the difference. Did you change orifice tube or stay
With original? Not trying to stir the pot, but I think you can get better temps.

 

[catbird7]

Replaced orifice tube with new "red" one. The gauge readings (high & low) were sitting in the garage prior to first test drive. 42 degree reading from the vent was driving down the road during test drive. Not sure what the outside air temp was (last Friday) however it was stinkin hot! This morning was the first I've driven the truck since and outside air temp was 48 degrees (which I love), so no AC needed. I'm sure we'll use it on the trip home later this evening & later this week is going to be a scorcher!

 

[catbird7]

Here's a little more feed back on my "old AC system", with 95 degree exterior temps the "feel" inside the cab is not much better than open windows. With the system a little over charged, I'm going to get the low side reading down to around 40psi and see how it works. Also noticed the engine temps push pretty high on dash gauge (it's the factory gauge, not mechanical) and I recently replaced the t-stat with correct motorcraft part. Having said that, isn't there something different with our engines regarding the thermostat housing and a ball or valve or something??? I simply pulled the housing replaced the t-stat and reassembled. I may have screwed up the reassembly which is causing the overheating???

 

[snicklas]

One thing I would make sure is you have air moving through the condenser, and the evaporator. If the evaporator can't pass air, it won't cool the air. How well does the air blow from the vents inside the truck? Make sure the condenser is free of debris and bugs....... you would be amazed how little crap in a core can prevent cooling. Does you fan at least spin while the engine is running. Even the "free wheeling" at idle helps a great deal. I know this isn't a fair comparison, but my 07 P71, at idle in the weather we've been having (90's with heat indices of 105-110) it will fog over the windows when I let it run and go inside for a moment. The other day, in cooler temps, the fan control module failed. which means the fan does not run at all, with this happening, the A/C was more like a Swamp Generator.......... even the breif trip home before I figured out what was going on, the "ram-air" was nothing like the fan running........ just something to check.

Also, since you are in the North, make sure you don't have anything in-between the various coolers. We had an 83 F-150, in Central Illinois, on a blistering hot day, it would run a bit warm, but nothing alarming. Dad and I were servicing the cooling stack along with adding a auxiliary transmission cooler. We found a very soggy piece of cardboard buried in the stack. Apparently the PO had stuck a piece of cardboard in there, and only got about half of it back out..... after we cleaned it all out, the truck ran cooler and the A/C worked better........

 

[gnathv]

What compressor is on your truck?

 

[catbird7]

I didn't buy the truck "new", however to the best of my knowledge it still has the original compressor. Still has FORD label on it an I believe FORD is "cast" into the housing. I knew the man who originally bought the truck.

 

[gnathv]

Is it the large square compressors?

 

[catbird7]

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Here's a couple pics of it.

 

[catbird7]

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Here is a good pic from the back while on the engine stand.

 

[gnathv]

That's not it. The one I was thinking of has service valves that if not fully back seated could cause your symptoms.
You either are overcharged, restriction in system, or poor air flow over condenser. Also could be combination of these.
400 on high side is your problem, need to find out what is causing it.

 

[gnathv]

Think about it as a pipe with a valve in it. You are putting 400 lbs of pressure in and getting 48 lbs of pressure out.
It should not take that much pressure to produce 48 lbs. also the temp of 134a at 48 psi is 52.3 f. You want less.

 

[catbird7]

Oh, I thought the highside reading was OK and the low side was the problem (remember I'm not an AC guy). What are the desired pressures for this system with R134A???

 

[gnathv]

The pressures depend on outside temp and flow of freon as well as flow across both coils. Generally a healthy system on a 90 degree day will be about 40 low side and 200 high side, give or take. There is no absolute, you must measure temp compared to pressure. 134a is very efficient making it very touchy. Generally you charge by weight. If your system is all good (no restrictions) this will give correct pressures. Don't give up, charge slowly and allow time for system to stabilize after each adjustment so you don't put in too much freon.