John Rygg

All, I have been battling my heater off and on for some time. I have searched the forum and have tried several suggetions and have not found an answer yet.

let me tell you my story.

when I have my tempature control set on the blue dot (cool ) setting at random times I get scalding heat coming from whichever vents I select.
I have checked out the #2 & #4 servos that control heat/cold settings and have determined that they are working correctly, I have even gone so far as to zip tie them in the full cold position and things still get very hot.

When it is hot, both the drivers fan and the passengers fan housing is very hot.

The only idea I have is that the differential pressure flapper valves are somehow stuck and is not redirecting hot air to the wheel wells when the engine gets hot. But is sending the hot air forward with a lot of pressure that gets by the closed hot/cold mixing valve.

at this point I am stuck on troubleshooting , or how to get at the differential pressure flapper valves. my car is a summer car so I have no need for heat and would be happy if the flapper valves always directed heat out the rear wheel wells. does anyone know if it is possible to force them to do this?

or does anyone have a fix ?

thanks in advance ... I don't need the Heat ! I live in Nebraska !!!

tafkai

they do sieze up , and getting to them is a bit awkward but by no means impossible .
under the car , with drip trays removed , you will see the 2 orange ducts either side of the bell housing . these connect to the flappers . take the hose off the flapper using the jubilee clip , and poke around inside to see if you can move the flap . if not either soak in wd40 , or hit with pice of wood !!!! .
if you dont need heat at all , you can just take the hoses off and tape up the holes .

JasonAndreas

If hot air is entering the cabin through the front vents then the temperature mixing chamber doors are opening (even just 1/8"), there is no other way for hot air to enter the front ventilation system. It doesn't matter if the rear flapper valves are sticking.

What you need to do is disconnect the servo arms from the mixing chamber doors, manually set the mixing chamber doors to full cold (horizontal), reattach the servo arms to the doors and then disconnect the electrical connector from the servo so that the CCU won't move the doors. That is the only way to "lock" the doors in full-cold mode, a zip-tie won't do it. If you run the CCU system with the top of the mixing chambers removed you'll see.

John Rygg

thanks for all of the good advice, the heat is at random times and is much greater then if I had the heat actually on. I have made sure that the mixing doors are completly shut. which is why I have to beleive that the heat coming in to the cabin is due to the flappers.

what is the best way to get to the flappers ? do I need to have the car on a lift ? or can I get to it by removing the rear tires ? anyone have pictures ?

Thanks again

dfinnegan

Not wishing to offend, I would like to point out that I, too, was conviced that my heat problem was not related to the flaps shown above with a green arrow and the servos, in red. I spent a great deal of time searching Rennlist, the internet, all of the documentation I could get my hands on and exploring the car. In the end, my problem was related to the green arrow'd mixing chamber flaps and a mal-adjusted server connection.

If the mixing chambers are closed, the pressure sensitive flappers in the rear can be wide open and no hot air can get into the passenger compartment. There simply is no other path for the hot air to flow through.

I really wish I had listened to Jason the first time he tried to set me straight!

I'm sure there are other problems that arise (bad ECU modules, etc), but in my case I really did have mixing chamber problems.

I hope you get your problem straightned out as I know how annoying that heat can be in the warm weather.

Cheers,
Dave

deep_uv

I have the same problem as John. I believe the mixing chamber doors are not shutting off all the way. Question: If I adjust the servo arm manually and reattach it so that it's fully closed (horizontal) as Jason describes, can I expect the door to always close back to that position when I'm on the blue dot? I'd rather keep the ability to heat the car in winter than totally disable it. I suppose I could just re-attach the electrical connection once winter is here too, but would prefer that it just works right. Thanks guys, Steve

GT-three

i have the same problem,I just poped the arm off the ball just now on servo#4 it doesnt feel as hot,but i still havent driven the car yet.I'll keep you posted.

JasonAndreas

No, you also need to disconnect the electrical connector.

The correct way to fix this problem is to replace the non-functioning servo, the disconnect trick is just to make the car driveable again.
Don't forget to reattach the arm but with the door in the full cold position (and the connector removed) otherwise the pressure from the rear main cooling fan will push the door open a tiny bit, just enough to cook you inside the cabin.

deep_uv

Thanks Jason. That's what I figured. The price just went up on those servos by about $90 to something like $219 at Vertex. They were $129 a couple of weeks ago. I was hoping to avoid having to replace it and instead be able to adjust it to close properly. And who knows, both servos may be bad. Oh well, that's the price we pay to have the kind of fun we have with these cars. I really appreciate your help. What a great site this is! Steve

dfinnegan

I replaced one of mine for $50 from LA Dismantlers; no affiliation.

I figure if it goes bad on me I can replace it three more times before the new cost. We'll see how it works out.