Need AC help...1979 300SD with ACCII. Heater nor AC worked when I bought it. Last year I replaced the AC compressor, drier, switches, orings, ect and the AC blew really cold. Last Winter I bypassed the servo to get heat. This spring I bought a re-tooled servo from Performance Analysis and installed it. All I get is hot air.
The compressor comes on and the low pressure side gets cold but not real cold; the high pressure side get hot. I added some freon for good measure but all I get in the cabin is hot air. I don't see any bubbles passing by the window on the drier. I verified the resistance of the thermostat pot and it's in spec (300-1200 ohms or something). I pulled the glove box to measure voltages at the amplifier and I found a piece of mystery rubber tubbing. One end is connected to a plastic module near the blower; the other isn't connected to anything thing. The hose is about 1/2 inch dia and if it were straightened out it would be about 2 feet long.
It loops under the air duct and comes up near the center console vents. Looking at pictures in the service manual it looks like it's connected to something called an "air jet nozzle" and it sounds like the other end should be connected to the temperature senor in the dash. Does this sound right?
There is also a small nice of hose (same diameter, about 3" long) that's connected to some white nylon looking housing that is attached to a cable that runners over toward the instrument panel area (it's kind of like a cable tie with a hose barb on it). I have no idea what that's about.
I'll try to get some pictures tomorrow to help illustrate what I'm talking about and I'm planning to give George Murphy at Performance Analysis a call to see what he knows but in the mean time...
1. Does anybody know where these two hoses connect?
2. Could the fact that they aren't connected to anything be responsible for my constant heat and no cold air?
3. If not, what's causing the constant heat and now cold air? The Amplifier?
Thanks

Are you using R-12 ?
Did you flush the system at the time you put all that new stuff into it ?
What kind of evacuation procedures did you follow at the time of refrigerant installation ?
What kind of oil are you using inside the AC system ?

" you added some freon FOR GOOD MEASURE ".... better to measure how much freon is installed since overfilling is the kiss of death in terms of performance... If you miscalculated due to some other problem and then got the total refrigerant over the max needed then you have added a problem to the diagnosis stream.

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

I do not know if this is happening to you but read years ago that if the Filter/Dryer is exposed to air fora a long time that they rust inside and that the rust can plug it up. The book I read said to replace it just before you fill the system.

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84 300D, 82 Volvo 244Gl Diesel

That hose you mention behind the glove box, you're right, it goes to a sensor in the dash, it's made of foam and deteriorates over time.
Can't help with the rest.

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83 SD

84 CD

I did flush the system. Once I had everything assembled, I had a service station vacuum down the system and I refilled it with Freeze 12. I added oil to the new compressor before I mounted it in the system. I don't remember the type/brand but I do know it was compatible with Freeze 12 and the compressor.
I did measure the pressure on the low side with the car/AC running. It was about 20 psi before and 40 psi after I topped it off.
I also replaced the drier when I did the compressor.
I did all this about 16 months ago and the system ran cold all the way up to December or so when I bypassed the servo and switched it over to heating.
The air it's blowing it really hot. It's as though something isn't stopping the hot water from flowing to the heater core (if that is in fact what should be happening) or something isn't engaging to block the the hot air from coming into the cabin.
Does anybody know if a bad amplifier would cause it to run at full heat?

Thanks, I'll reattach it.

I may be wrong, I havent worked on any of these servo systems yet, but shouldn't the servo stop the coolant flow? maybe shoot the place you bought it from an email.

and maybe go back and have them check pressures at the AC shop.

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1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.

Ok, I got the mystery hose squared away and I installed a new amplifier and the AC cools, sort of.
If the engine is cold and I move the thermostat to 85 degrees the AC comes on and blows cool air. Then I can move the thermostat down to 70 and it works fine. However, once the engine is at normal operating temperature and I turn the car off and then on again (like going to the store), I get nothing. The AC doesn't come on, the blower doesn't come on except for Defrost mode.
If the engine is cold and try to start off with the thermostat at 70, nothing comes on; I have to turn it to 85 and let it run for a minute or two then go down to 70.
I'm thinking it's got to be vacuum or some electrical problem. I'm planning to check the vacuum at the servo. The tach works sporadically; I'm not sure if that means anything.
Any thoughts on this?

BUMP
Still no advice on this one?

I think your tach has amp issues, some fixes last longer than others. I went with a new one, problem solved.
79 was the first year for SD's (116) and I'm sure things were different from later SD's (126).

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83 SD

84 CD

Thanks toomany
re the tach, I replaced the senor a while back and have a new forward cable but haven't replaced it yet.
I'm mainly concerned with the AC now (for reason obvious to the Northern Hemishere). Just wondering if that's an issue.
Still no input?
Leathermang-you were full of questions earlier. Still no pointers?