1993 toyota land cruiser air conditioning

My 1993 landcruiser air conditioner intermittently turns off. The fan keeps blowing. This started 3 years ago happening occasionally. Now it happens every few minutes when it is very hot outside. It will work 15-20 minutes or so when it is not hot outside. It blows freezing cold when it works. Compressor has been checked and is normal. Car stays charged with refrigerant.

When AC turns off, the dashboard switch remains pressed, and it’s light is on. I know of no interior thermostat in the car. Temp of AC is regulated by a slide lever on the dash.

Twice in the past two weeks I have had an alternator signal in the radio. This quits after I turn the car off for awhile. I know I need to check the alternator and to check for closed loop grounds in the system. Any ideas on the AC? Could current fluctuation from the alternator be turning off my AC? If so why does the AC work best when it is not hot outside.

There’s an engine coolant temperature switch in the AC circuit that controls an AC cutoff relay for the compressor clutch. This switch is in the circuit in the event the engine should start to overheat, the compressor is turned off so the condensor no longer releases heat onto the radiator. If this switch is malfunctioning, it will cause the relay to cut power to the compressor clutch, and the AC stops working.


You must check if the low pressure cutoff system (whatever type is used)is functioning.

Can’t help you with a alternator signal in the radio (is this by design) and I can’t place the term “closed loop grounds” in my automotive electrical terminology. Why don’t you just check all the grounds indicated on a schematic for resistance and just make sure they are there.

Alternators are checked with semi-special test equipment (if they have a load pile in them) you want to check your batterys standing voltage and the voltage when the alternator is putting out 75% of its rated max (its OK if the alternator does not put out its rated amperage,they seldom do). Check for the presence of a AC component in your alternators DC output,too much can cause odd things to happen (this can be checked with a multi-meter of moderate capabilites.)