Blend door?

[CyFi6]

I was wondering if there was any way to check the adjustment of the hot/col blend door and where i would find it? I was unable to locate anything about the heater or climate control system in the car in the TSRM and i searched all over this website and got nothing useful. Today i was driving around a lot and noticed with the fan on ac off and temp set to 65, warm air was blowing out the vents, warmer than outside it seemed. Normally my AC works very cold on the freeway, but today ac temps were significantly higher. It was blowing cool, but definitely not cold. When i turned the heater on, it definitely did get hotter, but it still seemed too hot with the heater off. I took a look at the valve in the engine bay, and something confused me. I thought when the "arm" was up, the valve was open. With the fan on ac off, temp at 65, i was getting warm air, the "arm" on the valve was up. I pulled the vacuum line off momentarily and the "arm" dropped down, suddenly i am getting burning hot temps out of the vents, put the vac line back on, cycled the temp up to 85 and back to 65, and was warm again and "arm" was up. Pulled vac line again and once again hot temps out of the inside vents.

I thought if anything, it should be opposite. I was under the impression that with the "arm" down, the valve was closed and shouldn't allow any cooling, but this is also irrelevant. With the climate control set to 65, shouldn't my blend door be keeping the hot air from entering my cabin in the first place? Is there any way to access this or at least test its functionality? Thanks.

 

[jetjock]

Look harder. It's all in the TSRM. Or you can always look at the servos and linkages.

Easiest way to check the system (including the air mix damper) is to put the system in auto and step ramp the temp set point slowly up and down. AC should be off because it needs to be treated as the separate system it is.

At 65 air should be cool (water valve off and damper blocking core), fan should be on high, and air should be mainly coming out of the center vents. As you increase set point the air should warm and flow should move towards the floor vents, ending up hot and mostly at the floor when you reach 85. The reverse should happen as you go back down. The fan will slow to minimum when set point temp is appx equal to in car temp and increase as you move away on either side of it.

There is a calibration procedure but it shouldn't have to be done unless the system was screwed with in a big way. Lastly, this is the second most complex system in the car. Unless you fully understand how it works you're going to be in for a struggle if something doesn't check out...

 

[CyFi6]

Ok, thanks for the help, but i cannot find the information i am looking for for the life of me. I looked through every section that has anything to do with heating or cooling, and the closest thing i found were diagrams of the system, but no testing or adjusting procedures, and this was all in the air conditioning section.

I will try what you said about doing the test with the auto functions. I did some searching earlier that said the valve is always open, unless A/C is on, which contradicts what you said, so there is some misinformation somewhere, are you sure the valve stays closed at 65? If so, there is my first problem, no matter what the temperature, my valve is "open" (though i get hot air whether or not the valve is open).

Is it possible that the static refrigerant in the AC system is heating from the engine bay heat and causing the evaporator to warm? I felt the lines in the engine bay, and they are way too hot to touch.

These past few days have been hell, combined with my engine running hot and having to run the heater constantly to keep the temps down. Something is very wrong and i cant figure it out, though i have some parts on the way. Now i find out my mailing system is all messed up, so the situation gets worse and worse. :aigo:

 

[Doward]

Did you look under "Functional Test and Adjustment" under the "Air Conditioning System" of the TSRM?

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AC&P=43

*edit*

As for your overheating problem, fix that FIRST. Pressurize the cooling system (you can loan-a-tool from Autozone for it) and pressurize to 16-17psi of pressure (you should be using a 13lbs cap) See if you are loosing pressure. If so, find the area you are loosing pressure from

Set up some priorities - to hell with the A/C until you get your cooling system for the engine fixed.

 

[CyFi6]

wow, i seriously spent like an hour trying to find that... though i dont completely understand what its talking about with having an O, R and W mark, the picture shows nothing like that, and i have no idea where to find the pictured servo. Then it talks about connecting different colored wires of a harness, what harness is it speaking of? Alll my other functions work fine, it is just the temperature control damper that is in question.

And i am working on the engine problem, i have parts on their way coming in the mail i cant do anything until they get here. Also, i have pressure tested the system and it held 17 psi just fine. I also tested the cap and it released at 13 psi like it should. There are no leaks or air in the system at all.

Thanks for the help!

 

[CyFi6]

Ok so i checked operation with a digital thermometer, and guess what, the blend door is not working at all. Its blowing a consistent 117-120 degrees out the vents on auto no matter what i set the temp to. Also, as i increase the temp, nothing changes, the vents blow out the top and dont gradually move to the floor or to the floor at all. I can set the mode to floor and it goes to the floor, but on auto it does not. The only change is when i hit 85 degrees the fan slowed significantly, but on 84 degrees the fan was blowing full.

This is a brand new problem that has happened all of a sudden, it was working fine just the other day.

 

[CyFi6]

Ok, i went out and tested again, and its in fact a little different than what i posted before. from 65-84, the temp is exactly the same somewhere between 125 and 130F. once i press to 85, the vac line to the heater valve gets vacuum, and the vent temp is around 160, and on auto, it shoots the air only at the floor.

So
65-84 setting, vent is at the main vents, shooting out air at 130 degrees
85 setting, vent is shooting at the floor, low fan speed, 160 degrees.

Im confused, this weird and new and i have no experience with vent controls under the dash, i don't know where to look for the different levers and arms that the tsrm points out. Again, just two days ago everything was working fine.

Also, the coolant heater valve is always "up" no matter what. Below setting 85, the line going to the diaphragm has no vacuum, but the arm stays up until i momentarily pull the line off and put it back on, then next time i go to 85 the arm goes back up, and wont go back down until i change the setting and pull the vac line on and put it back to release the pressure. Even with the ac on, the arm stays "up" unless i release it.

 

[jetjock]

The water valve should be closed at 65 and open above that. Even when it's closed it's designed to trickle some coolant through the core though. Fwiw the VSV that operates it is a common source of grief.

Read this regarding the in-car sensor:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AC&P=42

As for your cooling system you stated before the radiator was new. If not replace it.

 

[CyFi6]

Ok, thanks for the advice. I did a little more inspecting and upon taking the glove box off the actuator is in plain view. I tested all the sensors, they tested out fine, and it tested the modes and temperatures like you mentioned previously, everything seems to be working just how you described and the heat blend door seems to be fully closing just fine. After a drive there was a vent temp of around 115-116, i put my temperature probe in front of the recirc inlet where it was pulling air from, and ambient was about 109. I was able to stick my temperature probe through the foam seal around the evap box, after the evaporator and guess what, there's about 116 degree temps right there, before it gets even near the heater core. It looks like static refrigerant or just the metal of the evaporator is carrying heat from the hot engine bay into the fins of the evaporator and out to my ducts. What is up with that, is this supposed to be like that?

The reason i never felt this happen before may have been because i hardly ever used just my fan, but my ac performance was also down which confuses me. Help please if you have any input!

Thanks.

 

[jetjock]

Sounds normal to me. The air mix door doesn't completely seal off the evap. Appears you have nothing more than an AC problem which if I recall correctly is what you started out with. At any rate fix the cooling system first like Doward said.

 

[CyFi6]

That doesnt seem to make sense... I didn't know the blend door sealed off the evaporator at ALL. I thought any air that goes into the vents must go through the evaporator, as the blower is right before it and none of the ducts come until after the evaporator... I assumed when the ac was off the evaporator didnt hold and heat so it just blew air strait through.

How does this mean i have an ac problem? It has nothing to do with the ac system, the AC is off the whole time i have been doing any of these tests. The problem is that somehow the evaporator is carrying heat from the lines in the engine bay into the evaporator itself making all incoming air warmer. Are the lines in the engine bay supposed to be wrapped with insulation? It seems odd that they are not as they sit right next to the exhaust manifold.

Again, i am working on the cooling system problem, but i cant do anything until i get the parts in the mail, so thats why i am tackling this problem in the time being.

Thanks for any help.

 

[jetjock]

I should have worded that better. The air mix damper blocks the heater core. All air entering the system does go through the evap. Whether it goes through the core and how much is determined by the air mix damper. Your complaint is the air is slightly hotter than ambient with the AC off and CC set to 65 right? If so that's normal. If you're complaining about a lack of AC performance you need to look there after you're sure the air mix damper and coolant valve is working. As I said the AC needs to be treated as a separate system.

 

[CyFi6]

Ok, got it. My A/C is a whole separate problem, but my concern was one of the ac components (evaporator) was causing a problem with the regular air, so yes i wasn't directly concerned with the A/C performance, the thing is after i noticed these higher than ambient outside temps is exactly when my A/C performance dropped way down, which is why i thought it was related.