Heat and Air Issues (2 Viewers)

[cleophis1975]

Neither my AC nor my heat works. In the summer I'm burning up and in the winter I'm freezing. The buttons on the control module don't seem to do anything. And then, randomly, the blower will come on full blast, and I can do nothing to stop it except for turning the car off. And that's not ideal when traveling down the highway. I switched out the "head unit" in the dash with my other 80 that currently isn't running to no avail. Does any of this sound familiar or am I uniquely cursed with this heat and air issue?

 

[ceylonfj40nut]

By head unit, do you mean AC/Heater switch module or radio? Head unit is usually radio. Pls confirm. Module from a working truck is best to use to confirm. Not sure if the one you swapped was good to begin with.

 

[cleophis1975]

By head unit, do you mean AC/Heater switch module or radio? Head unit is usually radio. Pls confirm. Module from a working truck is best to use to confirm. Not sure if the one you swapped was good to begin with.

Yes, I was referring to the AC/Heater switch module. I knew head unit wasn't the correct term, but I wasn't sure what that module was called. I have thrown in a second unit from another Land Cruiser I have, but I cannot confirm that it works either, as the vehicle isn't running yet. That being said, the second unit did not fix the problem.

 

[Malleus]

The heat and A/C system is controlled by the switching unit in the dash, along with a the A/C amplifier behind the dash. The easiest check to make,to determine of any of the functions are working, is to move the heat control at the bottom of the unit from cold to warm. Watch the heater valve on the firewall and if it moves, the unit is getting power. If it doesn't you have an electrical problem upstream of the unit. The engine does not have to be running to perform this check, you just need power to the dash.

If that works, and you are reasonably certain you have a working A/C compressor (it's unusual for both heat and A/C to fail at the same time), you might have a damper valve problem. The details of what goes on behind the dash are below.

 

[Malleus]

The entire A/C section of the FSM is in the Resources section. LMK if you can't find it.

 

[jht3]

The easiest check to make,to determine of any of the functions are working, is to move the heat control at the bottom of the unit from cold to warm. Watch the heater valve on the firewall and if it moves, the unit is getting power.

also make sure the valve is connected to the push/pull cable. mine wasn't. the cable was moving, but couldn't open/close the valve!

but if you want heat now, disconnect the cable and manually open the heater valve to a setting you think won't freeze or sweat you out of the truck.

 

[surfpig]

Does your truck have the "AUTO" feature? I'm assuming if it's the LX, you do.

 

[cleophis1975]

Does your truck have the "AUTO" feature? I'm assuming if it's the LX, you do.

It does. But it doesn't do anything at the moment.

 

[cleophis1975]

For some added context, this summer I took my truck to AutoZone to have some freon added to the system. At that point, the FSM seemed to be working, just not blowing cold air. Shortly thereafter, the module quit working at all - no longer turning the system on or off.

 

[cleophis1975]

also make sure the valve is connected to the push/pull cable. mine wasn't. the cable was moving, but couldn't open/close the valve!

but if you want heat now, disconnect the cable and manually open the heater valve to a setting you think won't freeze or sweat you out of the truck.

I found the valve and the push/pull cable is indeed connected. Do I move the pin towards the middle of the truck to open that valve?

 

[KZN130Alabama]

Can you move the cable?

Sometimes the cable can break (like mine). You'll know when you've found the right setting. It will pour heat and you'll likely need to use the windows to adjust temp.

 

[surfpig]

Does your truck have the "AUTO" feature? I'm assuming if it's the LX, you do.

It does. But it doesn't do anything at the moment.

Did this just start recently, or since you've had the truck?

 

[cleophis1975]

Did this just start recently, or since you've had the truck?

This just started this summer. Last winter, I'm pretty sure my heat worked, but last winter, it wasn't my daily driver.

 

[surfpig]

This just started this summer. Last winter, I'm pretty sure my heat worked, but last winter, it wasn't my daily driver.

Do you get a lot of rain? Does your windshield gasket leak?

 

[cleophis1975]

Do you get a lot of rain? Does your windshield gasket leak?

How did you know that? When it rains really hard, it's like it rained in my floorboard.

 

[surfpig]

How did you know that? When it rains really hard, it's like it rained in my floorboard.

I was stalling for time till I could find the thread...



Climate Control - https://forum.ih8mud.com/threads/climate-control.31800/

There is a little box up under the dash, the A/C something-or-other thingie. It can fill up with water and it shorts out the whole system. I haven't found the thread yet where I have video of me pouring it out of the box... Anyway it's possible to take it apart and (very carefully) clean up the circuit board so it works again. I did that, then I reinstalled it upside down so water couldn't get in, until I finally found the time to replace the windshield/gasket.

 

[cleophis1975]

I was stalling for time till I could find the thread...



Climate Control - https://forum.ih8mud.com/threads/climate-control.31800/

There is a little box up under the dash, the A/C something-or-other thingie. It can fill up with water and it shorts out the whole system. I haven't found the thread yet where I have video of me pouring it out of the box... Anyway it's possible to take it apart and (very carefully) clean up the circuit board so it works again. I did that, then I reinstalled it upside down so water couldn't get in, until I finally found the time to replace the windshield/gasket.

I put my vehicle up for about 3 months and when I got it back out, it was raining. It was summertime and I had sandals on. I could feel the water dripping onto my feet as if it were raining directly into the cab. And that was also about the time the heat and air system started getting screwy.

 

[surfpig]

I put my vehicle up for about 3 months and when I got it back out, it was raining. It was summertime and I had sandals on. I could feel the water dripping onto my feet as if it were raining directly into the cab. And that was also about the time the heat and air system started getting screwy.

I'm totally willing to bet it's that "A/C System Amplifier (88650-60212) " under the dash. And the way the box is mounted, it fills up with water. Page two of that thread I linked describes what a couple of us did to fix it. That part is unobtainium.

 

[cleophis1975]

I'm totally willing to bet it's that "A/C System Amplifier (88650-60212) " under the dash. And the way the box is mounted, it fills up with water. Page two of that thread I linked describes what a couple of us did to fix it. That part is unobtainium.

When I get the chance, I'm going to pull this amplifier out and take a look at it. If it's damaged, I'll try to steal the amp from my other 450. It didn't seem like the "manual switch" option was a solution.

 

[surfpig]

When I get the chance, I'm going to pull this amplifier out and take a look at it. If it's damaged, I'll try to steal the amp from my other 450. It didn't seem like the "manual switch" option was a solution.

Didn't work for me. You'll probably find a little puddle of water in one corner of the box the boards are in. The slightest bit of mineral residue can short it out. Very carefully clean the boards up, reassemble it, and remount that thing upside down so water can't get in it anymore. Then get your windshield re-sealed.