Sick of AC questions yet? Trying to track down the root cause...

[mtweller]

'95 80 series (wife's truck)

AC's never been REALLY good, but last couple of summers it has gotten worse. I am confident the compressor is kicking off intermittently and am trying to confirm that now.

Symptoms:
Cold on highway. Cool (barely adequate) in slow moving / traffic, up until the high 90'sF ambient.
Needle has never moved. Just bought a scanguage the other day when it was 97 out, and the highest I've seen the WT since was 216, and the compressor never turned off.

Wife took it for a test drive today (95F ambient) and said water temps were climbing in slow driving conditions, but the max she saw was 212 on the highway portion of the trip (last bit of the drive). Air was cool when slow and cold on the highway.

So I'm thinking airflow.

I just replaced the oil in the fan clutch a few weeks ago w/ 10K cst. However, I can still stop the fan fairly easily with a rolled up newspaper, even at full operating temps. It is a Eaton.

Radiator and condensor coils look clean and undamaged. I'm thinking next steps are either t-stat / radiator flush. Or possibly a blue fan clutch. Recommendations??

Ramon

 

[Offroads4x4]

Your A/C most likely just needs a shot of 134 R-Freon to resolve it only cold when on the freeway.

I would back flush your cooling system with the thermostat out and the heat on hot so your heater cores get flushed as well. Flush until it runs clear.
Next I would replace the thermostat with a factory one.
You'll next need to decide if your going to run Toyota red or regular green antifreeze. Green is cheaper and you can find it everywhere as opposed to red.
You may need to use a Blue hub with the 10K-15K oil mod to move enough air to keep it cool if the flush and fluid don't do the trick.

 

[mtweller]

Thanks for the reply. I should add the system was purged and recharged last summer and there were no refrigerant leaks. The reason I suspect the airflow, is because of the highway speeds and the fact I can stop the fan w/ a newspaper. I think a new t-stat and coolant system flush is in order anyway. I WILL most definitely be going back w/ the red antifreeze.

R

 

[Offroads4x4]

You could also remove your block drain plugs to flush the block a little better.

 

[Coolstream]

If you have an Eaton fan clutch, the draining procedure is different than the other clutches. It involves proping the trap-doors open and draining it in a flat position. Tools R Us is the go-to guy for fan clutch knowledge and I just replaced the fluid in mine (an Eaton) with 17.5K. Highest engine temp seen on my scangauge since, has been 202 degrees in traffic, A/C on and 105 ambient.