My baby is a 94 3x locked fj80 but she is causing me some grief right now. I am really hoping someone can help. I have searched mud and all the rest of the internet but have found nobody with my problem. For some reason with the a/c on if it's cool outside the a/c for blow for a bit and then the heater will come on and I get 140 degrees out of the vents. I was thinking ambient air temp sensor (apparently 94 landcruiser doesn't have) or cabin air temp sensor (apparently only in units with climate control). Any ideas will help even if they are bad/stupid. I live in texas so 9 months out of the year you really don't want your car deciding what temperature you should be.
Air conditioner from hell
- Thread starter Lake trash
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- Thread starter
- #21
I drove it for a couple of hours yesterday in 90 degree weather. I was hoping it would act up so I could disconnect the heater valve but the stupid thing blew consistently at 45 to 50 degrees...I need to wait for a cool morning 
1. Heater valve wide open changes temp around 5-10 degrees
2. The odds of the temp door moving on its own are slim but don't say cant happen but, if it moves will make a big change.
3. Compressor turning off for some reason makes huge change in temp.
4. Refrigerant level changing temp that far is not going to be erratic.
5. The possibility of having two or more problems is very possible.
6. Weak fan clutch will cause pressure to rise shutting off compressor. (see #3)
Start by eliminating things as possibilities, easiest first.
Refrigerant pressures are read at High Fan, around 1500 rpm. Look at gauges. Highest High gauge reading and lowest low gauge reading.
The High pressure will be based on ambient temp (around ambient X 2.4 ish), low will be 15-25 psi and compressor will start cycling off if the low gauge starts dipping below 20 for a length to keep evap from freezing. This is normal.
"IF" the low side is running close to 30 psi, TXV valve is weak.
"Low" high side gauge reading means charge is low.
"High" high side gauge reading means too much refrigerant or, more commonly, fan issue. The high side safety switch will shut compressor off. Weak fan clutch is common here.
Run temp control to full cold. Go to heater valve. Look at cable attachment. Push on cable and see if the valve is closing all the way. If its open 1/4 of an inch that's around 10 degrees more in vents. I commonly have to adjust these.
"When" the issue happens again, look at compressor. Did it turn off? If it did, something is shutting it down. Controller, wire, relay, connector......
"IF" the compressor is still running when it happens, you eliminated a power problem.
These are a few basic steps to try to narrow down the issue. Intermittent problems are a pain.
2. The odds of the temp door moving on its own are slim but don't say cant happen but, if it moves will make a big change.
3. Compressor turning off for some reason makes huge change in temp.
4. Refrigerant level changing temp that far is not going to be erratic.
5. The possibility of having two or more problems is very possible.
6. Weak fan clutch will cause pressure to rise shutting off compressor. (see #3)
Start by eliminating things as possibilities, easiest first.
Refrigerant pressures are read at High Fan, around 1500 rpm. Look at gauges. Highest High gauge reading and lowest low gauge reading.
The High pressure will be based on ambient temp (around ambient X 2.4 ish), low will be 15-25 psi and compressor will start cycling off if the low gauge starts dipping below 20 for a length to keep evap from freezing. This is normal.
"IF" the low side is running close to 30 psi, TXV valve is weak.
"Low" high side gauge reading means charge is low.
"High" high side gauge reading means too much refrigerant or, more commonly, fan issue. The high side safety switch will shut compressor off. Weak fan clutch is common here.
Run temp control to full cold. Go to heater valve. Look at cable attachment. Push on cable and see if the valve is closing all the way. If its open 1/4 of an inch that's around 10 degrees more in vents. I commonly have to adjust these.
"When" the issue happens again, look at compressor. Did it turn off? If it did, something is shutting it down. Controller, wire, relay, connector......
"IF" the compressor is still running when it happens, you eliminated a power problem.
These are a few basic steps to try to narrow down the issue. Intermittent problems are a pain.
Fj80oregon
GOLD Star
Are your refrigerant levels correct that’s the first thing to check and nothing else. Get some cheep gauges harbor freight works fine they are under 50$. After that Than worry about controls or compressor or expansion valve or clogged office tube. A shop can also hook up gauges for under a 100$ if you don’t wanna invest in tools.
You can also just borrow/rent the tools you need from a local auto parts place like O'Reillys:
- Thread starter
- #25
I have gauges for every imaginable freon...I have just been lazy
- Thread starter
- #26
Wow that's alot of info, thank you very much. Am I reading right that the heater valve will only give a 10 degree above ambient swing? I am getting a 65 degree above ambient reading from whatever is my problem
P.s. gauges will be hooked up to it after work today
Will only raise vent temp about 10 degrees. If your vent is blowing 40, it will now be around 50.
Sorry, should have been more clear. I hadn't had my coffee yet.
Your OCD levels might not be high enough to run with this crowd. LOLI have gauges for every imaginable freon...I have just been lazy
- Thread starter
- #29
Ocd level is there but...on one hand I can drink till I pass out or I can play with my gauges.
Well tonight I played with gauges. Verdict is ...freon is good, pressures are good, and something IS telling the blend doors and heater control valve to open. - Thread starter
- #30
Time to pull the dash and start the Uber fun job of tracing wires to find out what is in line before the blend doors
I don't remember if its on our cruisers but, most Japanese vehicles with the same heater control valve, run a cable from the blend door to the valve. If the door moves so does the valve.
I'm not at home, so I cant pull up the diagram but, the control head normally directly drives the blend door motor. If the door is opening by itself then odds are its the controller. Still check the wiring just because. if something was added in (alarm, stereo, light switch...) the AC harness could have been pushed against something sharp and worn through.
I'm not at home, so I cant pull up the diagram but, the control head normally directly drives the blend door motor. If the door is opening by itself then odds are its the controller. Still check the wiring just because. if something was added in (alarm, stereo, light switch...) the AC harness could have been pushed against something sharp and worn through.
- Thread starter
- #33
I hope it's not the controller, I found a used one for $250 if it is. The thing that drives me nuts is that it does it when it is cool outside. It almost never does it when outside Temps are above 90 bit when they are in the 70s you will be running heat for probably half of your trip
- Thread starter
- #34
I removed the cable from the valve and zip tied it closed