Heater Servo Questions

[dshif]

Hello, I am yet another person working on my heater. I have been reading all over the forum and I am still unsure of my issue. It's an '85 if this helps.

1. I noticed no vacuum going to the water valve. I connected the vacuum from the cruise to it. My hoses are now hot.

2. Removed the radio and glove box. The servo unit arm is slid to the left (max cold). I removed the #4 vacuum line from the rear and no vacuum at all. I pushed the servo arm to the right (was really hard to hold) and I had heat until I let go of it (back to max cold).

3. I unplugged the sensor in the middle console and the servo didn’t move at all. I have never heard a sound out of it (no clicking). I noticed the fan wasn’t running in the console so I must need a new one. I unplugged the outside sensor and no change.

Would the vacuum on the back of the servo be strong enough to move the arm or is this done by the servo itself? It was hard to slide to the right and moves right back when I let go of it. I see that someone had been working on the vents before with the tape over the center vent hole (not sure why). What else should I check (a relay for the servo unit)? Seems like I have no power at all to it.

I bought this car this March and have never had heat so…

What suggestions do you have? I have looked at this link but still have questions so that I don't buy unneeded parts:

http://www3.sympatico.ca/dean.anders...tingSystem.htm

Thanks for your help!

[1982 Dragon]

Coolant and lines ok? I found my heat worked after a good rad flush

[dshif]

I had to replace the crank pulley over the summer so I flushed the system and added new antifreeze. It just bugs me that the servo unit does nothing...

[one2spooku]

Servo = vacuum controlled. The vacuum line is how it actuates. Lots of info online. There are various things to check. Pretty elaborate system.

Lots of possible reasons for the lack of vacuum.

[dshif]

I will try another vacuum source to see if it moves.

[Donn29]

Servo = vacuum controlled. The vacuum line is how it actuates. Lots of info online. There are various things to check. Pretty elaborate system.

Lots of possible reasons for the lack of vacuum.

This is wrong. It is vacuum powered, and electrically controlled. It does need vacuum to operate, but also needs the electrical to work right. The TSRM and TEWD books have lots of info. Start here for the TSRM: http://www.cygnusx1.net/Supra/Librar...aspx?S=AC&P=16 There is a link to an 85 Wiring diagram book in my Sig. It will take a bit of reading and you'll need a voltmeter I'm sure, but all the info is in there! Good luck!

[dshif]

Ok, I will get voltmeter. With it not moving at all I was thinking it is a possible electrical issue.

Thanks

[dshif]

Well, I have an update. I connected an 8' line to my servo unit from my cruise control and it went straight to heat. So, I have a vacuum problem. I will check the usual suspects and see what happens. For now... I will have heat for the winter .

Thank you for helping