I have a 88 Iroc. I bought it about a month ago and i knew the blower motor did not work. After a little diagnosis I found that the heater core return pipe had moved back towards the "firewall" or "bulkhead" and melted all the associated wiring to my blower controls, a/c pressure switch and vacuum controls.
At first I thought "That sucks, I will have to take the dash out" Today I decided it would be the day to do this. I removed the dash only to find out I had to remove the heater box as well. Ok, not that big of a deal. Then I noticed that ONE of the 4 screws that hold this box in was coming from the ouside in. Which is located conviently behind the evaporator core. So my question is....is this a common problem? Cause it was a muthaf'er! If so here is a list of thing you have to remove to get it.

Dash
Heater Core
Heater Box
A/C evaporator
It took me about 2 hours to get my wiring out and ready for repair. Then I ran out of daylight.


-Derek

 

I am the only one who's ever had this problem? I'm surprized at the retarded location where they put the pass through for the wiring.

 

As far as the melting. The heater doesn't get hot enough to melt the insulation. It either had to rub a hole through it or was operating under a high current draw for an extended period of time and melted from the inside out.

 

Back track down your wiring at the firewall, there is a fusible link coming off the starter solenoid that goes to the blower motor through that connection. It is possible that fusible link melted at some point and was replaced with regular wire. If this happened and there was an overload of the system, that wire and connector would get very hot.

 

It was melted externally from the heater core pipe.

 

The heater core isn't grounded so it shouldn't conduct any electricity.

 

NO. I mean the heat from the pipe which carries hot coolant to the heater core. The wires were in contact with the HOT pipe and it melted the wires. Because the pipe was not positioned properly/poor wire routing design.

 

Since you won't bellieve anyone until you see for yourself, take one piece of wire, drop in a pot of boiling water and let us know when the insulation melts off.

 

ya your right. I never even considered the melting point of the insulation, or the fact the pipe can never (under normal conditions) will exceed 300 degrees. The elting was still localized At the pipe and nowhere else. It's not like the pipe moves either cause it's bolted to the body.


I dunno. Thanks for straighting me out!

 

Generally the wire itself had to be hot enough from a large current draw. Leaning on the tube wasn't helping. Somewhere however, there still has to be a large draw.