Heater blower question

richde · 03-01-2008, 07:26 AM

Should it be running all the time on my '84?

When I turn the key to "run" it starts. The footwell blowers don't come on until I pull it's respective heater lever.

carolinatrophy · 03-01-2008, 07:56 AM

The Carrera HVAC system is pretty complex, so I THINK I'm right on this, but someone correct me if I have it wrong:

The rear (engine bay) blower should be off until you pull up the levers between the seats. Only then should it come on.

The twin footwell blowers are activated by the rotary knob between the seats, but these footwell blowers do not act independently. They will NOT come on unless the engine bay blower is already on and working - presumably to prevent the possibility of blowing exhaust gases into the cockpit.

The fresh air blower is activated by the dash levers and is totally separate.

So it sounds like something is wrong in your case. The heater blower should not be on if the levers between the seats are down. Nothing should always be on.

burgermeister · burgermeister's Garage

GOB (Love the alias!), that's my understanding as well. Seems to be how my car works, except for the footwell blowers, which appear to be seized.

richde · 03-01-2008, 11:46 AM

I'm really confused as why it would run constantly with everything else working properly. If the microswitch in the heater lever was stuck, you'd think that the footwell blowers would run constantly as well. I'm about to dive into the HAVC controls, but I doubt I'll find anything wrong relating to the heater blower.

Stuck or malfunctioning heater blower relay in the engine compartment?

carolinatrophy · 03-01-2008, 01:56 PM

Quote:

Originally Posted by richde

I'm really confused as why it would run constantly with everything else working properly. If the microswitch in the heater lever was stuck, you'd think that the footwell blowers would run constantly as well. I'm about to dive into the HAVC controls, but I doubt I'll find anything wrong relating to the heater blower. Stuck or malfunctioning heater blower relay in the engine compartment?

Well, I just went through all of this with another pelican, and if I can find the guy's name you might want to hit him up. He's a great guy and seems to know more about the HVAC system in these cars than anyone else on the planet. He even reverse-engineered his own modified relay so he could easily backdate the system. I'll PM you if I can find his name and email.

The footwell blowers wouldn't run constantly unless they were turned on. They do NOT work off the same microswitch as the engine compartment blower. When you pull up those levers, it turns the rear blower on. Then if you turn on the rotary switch between the seats, it sends a signal to the engine compartment relay to make sure the engine compartment blower is working, and if it senses that it is, it activates the footwell blowers. So you can definitely run the system with ONLY the engine compartment blower, but you cannot run the system with ONLY the footwell blowers working. Does that make sense?

As for the footwell blowers being seized, he helped me with this too. They generally seize because they generate an enormous amount of heat, which melts the plastic cage around the shaft of the blower. This plastic melts around the shaft and binds the motor up. Generally if this happens, when you turn the rotary switch between the seats it will instantly blow the heater fuse in the fuse box. But shockingly, it's hard to burn these footwell blower motors out, even when they are bound up like that. Generally you can remove them, carefully scrape away all the melted plastic, clean them up real nice and they will work fine again.

Hope that helps, and YES! BRING BACK ARRESTED DEVELOPMENT!

richde · 03-01-2008, 02:22 PM

Problem found, the potentiometer under the dial is missing. Can't seem to find the wires leading up to where it was either.

The heat exchanger temp sensor connector is missing as well, I know there's one somewhere, I saw the sensor in the heater box.

fun fun fun

burgermeister · burgermeister's Garage

I just un-seizd my footwell blowers by liberally dousing in WD-40 and giving a few very sharp raps on the blower shaft end (the end with the squirrel cage) with a small hammer. Freed them right up. Haven't re-installed and tried them out yet, though - gotta get some 10A fuses ...