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Topic: 1984 Elan climate control?? issue (Read 1661 times) previous topic - next topic

1984 Elan climate control?? issue

Hey guys, I cannot grasp the understanding of the climate control they used in the 83 and 84 birds, this is the system with the digits printed on the lever cluster ranging from 65 to 85 degrees. The slider for hot and cold works and the cable goes up to this thermal reader thing at the top of  the dash. My problem is that I get no heat. All cables and vacuum are hooked up ( to the best of my knowlage and what I can see). The heater core is ok too. What I can tell you is I noticed if I leave the blower running and I shut off the car, after about 2 minutes I start to feel heated air. as soon as I start the car again, heat goes away. This system looks to be a vacuum nightmare. What could this be??
 

1984 Elan climate control?? issue

Reply #1 –
Welcome!!!

I really don't know much about these systems, but sounds as if the blend door is being pulled into the A/C position, and as the car sets is released when the system equalizes... With loss of vac to the system, I'm guessing it should default into heat or defrost operation...


No I haven't helped much, if no one has seen such a problem you may need to locate the factory service manual to get troubleshooting procedures...

Tom

1984 Elan climate control?? issue

Reply #2 –
in the engine bay passanger side near where the ac lines exit the firewall,,

Do you have a little tiny three way vac valve?  One small black line should traverse the firewall up to the vac distribution block.  One line should run into the passanger side fender well.  The other line should travel through the firewall into the car.  This is the main vac feed for your hvac.  trace that perticulair vac path out and make sure it is connected.  IIRC, it connects to a canister to the left of the glove box on the inside but you have to tip your glove box out to see.

1984 Elan climate control?? issue

Reply #3 –
Yep, I do and it all looks to be hooked up properly, no cracks in vacuum lines or the such either.. The blend door, Im trying to figure where it gets it's vacuum signal from..

1984 Elan climate control?? issue

Reply #4 –
Quote from: freakaftr8;217793
Hey guys, I cannot grasp the understanding of the climate control they used in the 83 and 84 birds, this is the system with the digits printed on the lever cluster ranging from 65 to 85 degrees. The slider for hot and cold works and the cable goes up to this thermal reader thing at the top of  the dash. My problem is that I get no heat. All cables and vacuum are hooked up ( to the best of my knowlage and what I can see). The heater core is ok too. What I can tell you is I noticed if I leave the blower running and I shut off the car, after about 2 minutes I start to feel heated air. as soon as I start the car again, heat goes away. This system looks to be a vacuum nightmare. What could this be??


That thermal  reader thing that your temp control cable goes to is called the "in car temperature sensor".  It controls the vacuum to a vacuum operated servo motor. The servo motor controls the cable to the temperature blend door.

More vacuum on the servo motor moves the blend door towards cool. Less vacuum moves the door towards heat.

The temp sensor has three hoses on it. A black hose supplies vacuum, a black/tan hose takes vacuum to the servo motor and a hose (unknown color ) that brings air up from the blower motor.

1984 Elan climate control?? issue

Reply #5 –
Ok I get it.. But what is the unit that is on the heater core hose. It has 2 vacuum lines and an electrical connector going to it. I also noticed that im getting vacuum from the hose going into the dash from the 3 way splitter up on the passenger side firewall... This is odd becaude if I disconnect that hose, I dont believe there should be any vacuum whatsoever, except the unit coming off the heater hose on the heater core..

1984 Elan climate control?? issue

Reply #6 –
Quote from: freakaftr8;217907
Ok I get it.. But what is the unit that is on the heater core hose. It has 2 vacuum lines and an electrical connector going to it.

It's called the "thermal blower lockout switch".
With the HVAC function lever in HEAT position and a cold engine it locks out the blower (the electrical part) and holds the outside air/recirc door in the recirc position (the vacuum part).

Quote
I also noticed that im getting vacuum from the hose going into the dash from the 3 way splitter up on the passenger side firewall... This is odd becaude if I disconnect that hose, I dont believe there should be any vacuum whatsoever, except the unit coming off the heater hose on the heater core..


The 3 way splitter is a check valve.  Air can only go in one direction.
On one side there is the manifold vacuum from the vacuum tee.
On the other side is a the hose to the HVAC and a hose to the vacuum reservoir.
The reservoir maintains vacuum on the HVAC when the manifold vacuum drops.
The thermal blower lockout uses vacuum from the HVAC side of the check valve.

1984 Elan climate control?? issue

Reply #7 –
Well I found out something. That big vacuum solenoid is going to cold side blend door when I start the car, and will not change at all unless I unplug the big black and tan line then it springs to hot side and viola, I got heat! It is always under vaccum and it shouldnt be. This is controlled by the thermal air switch on the top of the dash. I think it might be faulty.

1984 Elan climate control?? issue

Reply #8 –
Reread post 5.

The only input that could be missing is the air from the blower.

From the 84 EVTM:
"Air is picked up by an air scoop from the high pressure side of the blower and piped to the in-car temperature sensor.  Air flows through an aspirator in the sensor, which draws in-car air over a bi-metal strip. The bi-metal strip is linked to a vacuum regulator, which converts air temperature to modulated vacuum. This vacuum is sent through the black/tan hose to the servo motor."

1984 Elan climate control?? issue

Reply #9 –
one fine day softtouch, we might met up.,,
you are something else thats for sure.:bowdown:

1984 Elan climate control?? issue

Reply #10 –
Hey guys, you have been a great help to me on this subject and I got the issue fixed!!! I should let you know that the thermal reader in the dash should be cleaned from dust and debris once in a while. I sprayed it out with elecronics cleaner, viola! I have control now! Thanks again!