Hot air in passenger compart.! Evaporator?

[Upset99]

I have two running E9s. They both have the same problem. Even when the A/C is not running, the in compartment A/C evaporator is cranking out HOT air. I believe this to be the culprit because I had the A/C installed on one of the cars and after installation, I experienced the problem.

Any suggestions?

Note: the site has an editor...it wont let me write "c-o-c-k-pit! LOL!

 

[jhjacobs]

When I first got my coupe I had a similar problem. At first I thought the heater core was always hot and the air directors were not sealing. I then took a look at the fresh air intake - it is directly behind the firewall. I also noticed my firewall seal was basically rotted away letting hot engine air directly into the fresh air intake. I replaced it with a new generic push-on O seal from JCWhitney (after being set back in my chair by the price of the OEM seal). This seems the have mostly cured the problem for me at a cost of about $19 and 5 minutes work. Much better than ripping apart the complete center console....:roll:

Worth a look.

 

[abe3.0CSi]

A couple of other issues....hot water still circulates inside the heater core even when you turn it off. Its possible that if your A/C is off that the engine compartment gets sooo hot in these cars that some heat is transmitted via the hoses/pipes/ into the evaporator....this is a wild guess. Also, again these cars get sooo hot that you could be getting heat from the firewall area as well as the downpipes and transmission area. Make sure you seal every little hole at the fire wall. I wonder if these plastic/rubber tubes that connect at the end of the two drains (sold by La Jolla Ind) might prevent further heat into the firewall area.
I know my cabin always gets a little warm...even when everything is completely shut off.
abe

 

[jhjacobs]

The "always active" E9 heater core is a real bonus. I have purchased a salvaged Mercedes heater core electric bypass valve to solve this problem at some point when I have the engine out.

I've also been eyeballing my air-box for a rebuild (there are some great notes on this somewhere in the old threads); I just can't work up enough nerve to start this project because I figure it is about 1 month of down time. I'm sure the little control levers need aligning and the flapper seals are non-existent. I also know I have a tiny leak in the heater core that surely won't get better with time.

Maybe a good solution would be to permanently bypass the heater core and install electric heat - I do have an 80A alternator?!

My coupe was a real sweat box until I sealed the firewall. The fresh air is almost cool now where it used to be flat out hot. Sealing the firewall is a simple first step that is like chicken soup.

 

[Tyler]

Somewhat related, can anyone tell me the position of the levers to maximize the amount of fresh air coming into the cabin? I don't have A/C and my consol is all german.

I can get good airflow (although its usually warm) to the upper defrost vents, but can't find the combination of levers that blows a meaningful amount of air out of the main cabin vents.

Regards,

 

[blumax]

Max fresh air

As stated above--do seal off all obvious hot air leaks from engine compartment--BTW--our coupes really like all 3 seals in place--at the radiator support, the firewall and last at the base of windshield/windscreen--this helps everything work better.

Max outside air:
1) Far right lever is pushed all the way to the right--I believe same fo you guys who still drive on the wrong side of the road and steer from the passenger seat
2) Center lever--I keep it in the middle to equalise air flow direction to defrost and to floor.
3) Center heat control all showing blue--no red
4) Far left fan switch always at first notch--to be open--I also use the fan motor at first or second notch to drive air inside the cabin.
4) If side windows are closed--the slight air pressure created from incoming air driven by the blower fan will also keep outside fumes

BTW--our coupes have a direct major heat source from twin exhaust pipes that are running at several hundred degrees F just beneath the passenger--eerrr--drivers feet in the RHD types--and then with some time for heat soak--your shifter, hand brake handle, transmission, etc join in to become radiators of more heat in their own right.

I would be very interested in hearing of solutions that others have come up with to minimize the problem. I have though of fabricating a heat shield similar to those found on the next edition models up to present day BMW's. If one could be professionally done and could be replicated at reasonable cost--I think every serious Coupester would want a practical heat shield kit--I would buy one in a NY minute!!

PS--good news--I just spoke with carl Nelson aka Bimmer Doc in La Jolla, CA--he is working on this vey thing as we were chatting.

 

[decoupe]

Heater Core Bypass

While getting the core rebuilt I used the low tech plumbing solution to allow me to still drive and found some relief to the passive heating side effect of the always on heater.

Two copper 90 degree elbows and a short straight section of pipe. Disconnected the heater in/out so the circulation continued and drove it all summer that way. Stuck the rebuilt heater back in around september when the mornings got cool. I've been looking for some compact inline T valves to put in so I would have a summer off position but haven't seen anything small enough.

Doug