FJ62 A/C cooling issues (1 Viewer)

[grayfj62turd]

I have a 1989 FJ62 with A/C cooling issues. Upon turning the truck on and switching to A/C, the air blows very cold. After driving for 15 minutes or so the air temp begins to rise to almost no cool air at all. This pattern repeats after the truck cools off for a few hours. The air temp never returns to cold when driving over an hour. I switch the truck air flow to recirculate and it doesn’t help at all.

The A/C was just serviced and they said the refrigerant (R134) was low. I don’t know if they vacuumed out the system and replaced with refrigerant or just added more r134. The compressor, dryer, evaporator, etc. all appear to be original to the truck. 234k miles

Any suggestions?

Thanks to all!!

 

[LA Z]

Does the compressor cycles on and off when it happens?
Have you clean your evaporator recently?

 

[SteveH]

The truck came with R12, so if it has R134a, it's been retrofitted and will show valve adapters on the compressor. Buy yourself some high/low gauges from Harbor Freight and record the high and low side pressures as the system runs. As LA Z said, watch for compressor cycling. You might also watch for bubbles in the sight glass, if the system still has one. There is much you can do yourself before you take it to a shop.

 

[1972FJ55]

This sounds like an expansion valve problem. The only way to know for sure is to have gauges attached when it looses cooling. If the low side is extremely low or into vacuum, it's time for a new expansion valve and drier.

 

[grayfj62turd]

Does the compressor cycles on and off when it happens?
Have you clean your evaporator recently?

Compressor does cycle and I haven't cleaned the evaporator - I will this evening. Thank you!

 

[grayfj62turd]

The truck came with R12, so if it has R134a, it's been retrofitted and will show valve adapters on the compressor. Buy yourself some high/low gauges from Harbor Freight and record the high and low side pressures as the system runs. As LA Z said, watch for compressor cycling. You might also watch for bubbles in the sight glass, if the system still has one. There is much you can do yourself before you take it to a shop.

I'll look at it this evening. I have a/c hoses Thanks!

 

[Engineer8000]

The compressor only cycles on thermistor input (freeze up) or from low pressure (pressure switch), indicating possible low charge or low air flow through the evaporator.

 

[WoodnotRust]

This sounds like an expansion valve problem. The only way to know for sure is to have gauges attached when it looses cooling. If the low side is extremely low or into vacuum, it's time for a new expansion valve and drier.

I think that @1972FJ55 is exactly right. Two years ago my wife's LR3 experienced the same problem and a reliable mechanic I trust diagnosed it as the expansion valve. That said, I chose to replace the compressor at the same time so I can't say definitively which of the two repairs solved the issue...but the LR3 cooler has worked flawlessly since.