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93 Ls400 A/c Issues


timntools

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I'm looking to buy one of these, but it has an issue with the air. When the AC is in the coldest position, only the very right vent blows cold air. All of the rest blow warm to hot air. I'm assuming this is a bigger issue than just the heater core...

anyone ever experience something similar? My way of thinking is in lines with a vac line or some kind of damper stuck, but I don't know squat about how a toyota system of this year works. (well, toyota of any year for that matter) :(

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Ouch. Sounds like a vacuum or mechanical operated internal damper/door has malfunctioned. It's all inside the dash. Good luck, as this won't be easy or cheap to repair.

thats what I was thinking, but didn't want to hear...

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maybe simpler than you think. when i first got my LS (last march) it was still cold and the heat was great. when the summer came the heat just kept comming no matter what the ac was on, and the only way to stop it was to close the vents completely. changed the spark plugs, wires, coils, and rotors and haven't had an issue since (needed to refill though). not saying this is your problem but these cars are very well built. just something to consider...

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I'm looking to buy one of these, but it has an issue with the air. When the AC is in the coldest position, only the very right vent blows cold air. All of the rest blow warm to hot air. I'm assuming this is a bigger issue than just the heater core...

anyone ever experience something similar? My way of thinking is in lines with a vac line or some kind of damper stuck, but I don't know squat about how a toyota system of this year works. (well, toyota of any year for that matter) :(

Your symtoms don't exactly apply to this test buy the test is simple and takes little time...

There is an engien coolant flow control (HOT water for HEAT) valve inside the engine compartment at the top center of the firewall. The valve is operated in parallel with the blend/remix door via a push/pull cable. If you toggle/move the climate control system temperature control from maximum cold to maximum heat you should be able to see the cable move the valve from fully closed to fully open.

Assuming that work correctly then.

The extreme right and left dash airflow outlets are always open unless closed manually, check that left one to see if someone has closed it.

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  • 1 year later...

Trying to revive an old thread...

My 93 LS400 just started to have this problem (cool/cold air from rightmost vent, warm/hot air from all other vents). This happened after I replaced a leaky heater control valve, which is by the firewall in the engine compartment.

I noticed that this valve is controlled via a cable that goes through the firewall from inside the cabin/dash area somewhere. The valve no longer moves as I change the temp control from max cold to max hot. Now if I manually open the valve, I'm able to make the right vent blow cool air and the other vents blow hot air. If I close the valve, the right vent blows cold air and all other vents blow room temp air.

I've done an A/C system diagnostic procedure I found on the web to check all sensors and servomotors, but no errors showed up. All fuses are still good.

To summarize:

a) the motor that controls the heater valve doesn't seem to work. I separated the cable from the valve to minimize resistance but it still doesn't move.

B) Routing of air is permanently stuck on warm/hot air to most vents, cool/cold air only to the right vent.

Does anyone know what's going on here? Any help would be appreciated, Thanks!

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Trying to revive an old thread...

My 93 LS400 just started to have this problem (cool/cold air from rightmost vent, warm/hot air from all other vents). This happened after I replaced a leaky heater control valve, which is by the firewall in the engine compartment.

I noticed that this valve is controlled via a cable that goes through the firewall from inside the cabin/dash area somewhere. The valve no longer moves as I change the temp control from max cold to max hot. Now if I manually open the valve, I'm able to make the right vent blow cool air and the other vents blow hot air. If I close the valve, the right vent blows cold air and all other vents blow room temp air.

I've done an A/C system diagnostic procedure I found on the web to check all sensors and servomotors, but no errors showed up. All fuses are still good.

To summarize:

a) the motor that controls the heater valve doesn't seem to work. I separated the cable from the valve to minimize resistance but it still doesn't move.

B) Routing of air is permanently stuck on warm/hot air to most vents, cool/cold air only to the right vent.

Does anyone know what's going on here? Any help would be appreciated, Thanks!

The cable that opens/closes the hot water control valve is itself driven by the reheat/remix servomotor inside the plenum area. The cable has undoubtedly slipped off the other end.

Sorry, not good.

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wwest, thanks very much for the reply!

Is this something I can fix myself? I usually do easy/intermediate repairs myself, but leave the difficult jobs to the auto mechanics. I'm hoping it will be accessible maybe by taking off the glove box or something...

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wwest, thanks very much for the reply!

Is this something I can fix myself? I usually do easy/intermediate repairs myself, but leave the difficult jobs to the auto mechanics. I'm hoping it will be accessible maybe by taking off the glove box or something...

As you move the control from HOT to COLD the servomotor should travel end to end accordingly. Follow the sound and if you can see/get at the servomotor then go for it.

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