Automotive Air Conditioning Information Forum

Welcome back.
Would still like to see numbers using a full load test:
1500-1800 RPM
max fan
max cool
recirc
doors open
hi psi
lo psi
ambient at least 80°, please provide ambient
vent temp

Is there a mechanical fan? If so, a fan clutch? They only last 2-3 yrs, as far as AC is concerned. AC performance will degrade waay before engine will overheat
Yes please check electric fans. Are they on the entire time the comp is on? That is how I personally prefer it.
I have had electric fan motors weaken and need to be replaced.
Condenser mounted no more than 1/2" away from rad? With air dams all around?

Remeasure the ohms that you installed...resistors can degrade, especially these days as they are made in Cxxxa. In fact, at this point we are used to having any electronic component degrade with time

Remember, the first word in Air Conditioning is AIR

report back

Confirmed with owner that both fans are running. They are the only fans and it is a factory setup. Yesterday when running it, outside temp was 92, truck grill temp read 119, low side 27, high 275, center vent temp 53, blower one notch below high, doors and windows were closed, set to recirculate. This was at 1200 rpms.

If low is 27 psi, then your core is cold. In fact, depending on the gauge accuracy, 27 is just a tad below freezing, be sure core is not freezing up

Also could check for reheating due to heater core not fully shut off...either hot water valve or faulty damper

Dgreen wrote: ↑Fri Jun 24, 2022 6:24 am This truck has electric fans. My question is, does the performance of electric fans diminish as the wear out? I will admit that I didn’t confirm that both fans were running. It made such a loud sound when the fans ran it sounded like a plane taking off. I will follow up on that.

The performance of electric fans surely can diminish over time. But if the fans were roaring as loudly as you mentioned, they're probably working as they should.

Another thought: Even though the owner replaced the condenser with a new component, it's not unheard of that the new part is defective in some way. A couple years ago, I heard about someone having to replace a new condenser with another new one because manufacturing debris was inadvertently left inside the first condenser, blocking some of the micro-passages.

Other than the condenser and TXV, which you already replaced, leads us back to the cycling switch or thermister, and using a scan tool that can "see" and test the sensors feeding information to the BCM—both of which were pointed out by other consultants last year.

I got a chance to do some more testing on this truck this morning. Same problem, vent temps aren’t cool enough. Pressures were 25 and 240. Vent temp 57. It was 90 degrees outside. Condenser temp ranged from 130 to 140. Truck running 1200 rpms. Owner says the radiator fans no longer run on high all the time. I suspect getting the overcharge corrected when I changed the expansion block fixed that. Anyway, clamped off a heater line and the vent temp improved to 47. Not sure what the problem would be, but the owner said he was going to put a shutoff valve in the heater hose. If this does cure the problem, we will probably have take the resister that I added to the evap temp sensor out so that it doesn’t freeze up.

Owner just txted. He stopped at a store after he left my place. He left the truck running and it is blowing cold air. No shutoff valve installed yet.

Sounds encouraging. 47° is a good number.
You can block off the heater water circuit in some cars without worry, but not in others.
I have done so myself on a couple of vintage cars.
The vacuum operated heater control valves are famous for not closing all the way, not a good choice of control in my opinion.
Again, with a lo of 25 psi, the core is plenty cold.
I prefer my condenser fans to be on at all times. In the past, I have rigged up a relay triggered by the comp on wire, so that the fans run always if comp is on.
Also, can check temp of pipe in and pipe out of condenser and compare. Temp drop s/b at least 20-25°, any lower means blunted condenser function.
Most air cooled coils s/b able to give a 30° drop. Properly functioning car radiators and residential condensers, for example, will exhibit a 30° drop.
It is hard to interpret your cond temp of 130 to 140....which pipe?, and the other pipe not taken for comparison.