Passenger heat airflow significantly less than driver side

dbrisson · 03:01 PM

82 SC auto heat

Drivers side flow, def and side vent always pushing more air than passenger side unless the blower is on. I replaced the rear hoses to the heat exchanger thinking this may be the issue. No change. The passenger side flapper is moving with the auto heat controller.

Is this normal or should I still keep looking? Any thoughts?

lindemans · 03:31 PM

Both sides have a blower unit in the footwell area, behind a plastic cap peeking through the carpet.
Attached to the blower unit is a 10 Amp fuse that is known to fail; the 10 Amp is known to have too little margin for the blower unit.
I had that in my 3.2 a while ago.

I would check yours and (if required) replace with a 12 or 15 Amp one to prevent it from failing again.

dorschman · dorschman's Garage

Maybe the same problem here?

My driver side heat will work but I have to pull the lever up much higher than the passenger side to get the heat to turn on. Could this be a blower issue as well or likely somewhere else to start?

erik

lindemans · 02-12-2008, 09:10 AM

If you open heating all the way, and direct the flow to the windscreen, you should feel the warm air blowing out of the openings in the upper dash.
If there is significant difference between either side, it is likely that one of the footwell blowers is not working.

They are behind a carpeted panel on the side of the footwell; in most cases the fuse on the blower unit.

tonythetarga · 02-12-2008, 09:17 AM

AUTOHEAT is a bit of a different monster with its own set of problems and fixes. Do a search for a user by the name of 'mysterytrain' and read his threads. He knows what he's talking about and hopefully, has the answer to fix your issue.

As far as the footwell blower fuses go, if it was designed for a 10 amp fuse and it blew, it blew for a reason. Putting in a bigger fuse only moves the resulting damage to your blower or worse, starts a fire from overheating the wire because the fuse did not blow when it was supposed to. Sorry, but that is just bad advice.

lindemans · 02-12-2008, 09:23 AM

I agree with the general statement about fuses; having an MSc in EE I know a blown fuse NORMALLY is the cause of something else than the fuse itself.
Yet the 10 Amp is known to be tight in relation to the current the blower may pull and may blow without actual blower problems.

That's why P dealers here recommend building in a little extra margin.
If there is a real problem that makes the 10 Amp fuse go, so will a 12 Amp one.

In my case replacing the blown fuse solved the problem some 4 years ago, to date without issues.

tcar · 02-12-2008, 09:23 AM

Quote:

Originally Posted by lindemans

Both sides have a blower unit in the footwell area, behind a plastic cap peeking through the carpet.
Attached to the blower unit is a 10 Amp fuse that is known to fail; the 10 Amp is known to have too little margin for the blower unit.
I had that in my 3.2 a while ago.

I would check yours and (if required) replace with a 12 or 15 Amp one to prevent it from failing again.

SC's do not have footwell blowers like Carreras. So that's not the cause on his car.

I'm guessing the flappers in the back are not opening the same amount, or the exchanger to body hose is leaking.

lindemans · 02-12-2008, 09:25 AM

Confused now, dorschman's subtitles indicate a 87 coupe....

tcar · 02-12-2008, 09:31 AM

The original post is dbrisson; '82 SC.

Isn't that what you were responding to?

SC-targa · 02-12-2008, 12:18 PM

If the SC has AC then the tubing form the blower motor to the heat exchanger is a smaller OD to fit between the AC compressor mount and the engine cooling fan housing. That restricts air flow to the passenger side.

Regards,

Jerry

tcar · 02-12-2008, 01:45 PM

Same diameter both sides on all 3 SC's I've owned, all with A/C.

The passenger side tube is a lot longer, though.

Might want to check, sometimes the passenger side tubes get crimped where they run under the compressor. Pretty common.

dorschman · dorschman's Garage

Sorry for the confusion. Yes, mine is an 87. I just thought the problems sounded potentially similar. I will take mine out and see if the overall output is the same passenger and driver side at full blast (without help from the auto) on the windshield and at the foot wells.

Erik.

dbrisson · 02-12-2008, 04:34 PM

Thanks for the help so far. I went out last night and found the passenger side HE tube was not fully connected, fixed that and more flow but not equal. Also found the drivers side flapper valve was not matching the passenger side, adjusted that. It was not closing as much. With the key on, engine off, auto heat to 3, rear fan running there is still a difference in flow between the sides. So maybe some cable adjustments in the the front area are out of whack. I couldnt test it today since it snowed and iced over and I didnt want to chance it, plus I was in a rush due to some important meetings in the morning. I will post some more findings tomorrow.

The footwelll post had me searching but I found no blowers except for one in the center of the front trunk area and it works ok, I think the switch contacts are dirty/ worn since it sometimes works great other time I have to 'jiggle' the switch. Looks like a trip to the classified section for a set of heater controls....

dbrisson · 02-12-2008, 04:39 PM

Thanks for the help so far. I went out last night and found the passenger side HE tube was not fully connected, fixed that and more flow but not equal. Also found the drivers side flapper valve was not matching the passenger side, adjusted that. It was not closing as much. With the key on, engine off, auto heat to 3, rear fan running there is still a difference in flow between the sides. So maybe some cable adjustments in the the front area are out of whack. I couldnt test it today since it snowed and iced over and I didnt want to chance it, plus I was in a rush due to some important meetings in the morning. I will post some more findings tomorrow.

The footwelll post had me searching but I found no blowers except for one in the center of the front trunk area and it works ok, I think the switch contacts are dirty/ worn since it sometimes works great other time I have to 'jiggle' the switch. Looks like a trip to the classified section for a set of heater controls....

DRACO A5OG · DRACO A5OG's Garage

Just fixed my Heat Flaps by adjusting the cables underneath the car. Both flaps did not close all the way causing a leak from the heat exchangers. There was a larger gap on the passanger side and it never really heated on that side. Now it's nice and toasty.

Now to fix my footwell blowers, I hope it just the 10 amp fuses.

I know it's not the Auto Heat Center Module because I hear a click after 1 to 2 and the heat gets hotter but the Footwell Blowers don't work.

BTW, does anyone know where the inside heat sensor is on the Targa? Bentley states between the visors but I swear there is no such thing unless it is burried behind the leather lining