OK, I just bought an 87 Turbo II.

The Heater will blow hot, then it blows cold. Sometimes it will go back to hot. The Temp gauge is running normal. Coolant is at a normal level. What is worng and how do I fix it?

Thanks Rob

 

The only things that immediately come to mind are replacing 1 or more of these:
--thermostat
--waterpump
--flushing the system and replacing the coolant

--possibly a very loose belt(s) that spins the waterpump and with a remote possibility that the waterpump is seizing up, you will lose coolant flow, thus causing your heater core to cool down and lose heat.

 

I should have included this in the first post.

I put a new Radiator in because the old one split the plastic top tank. New Thermostat and new coolant.

I did wom web searching and found a referance to the Logicon sensor or switch. Not sure what it is yet or where it is located.

Trying to do searches between the Boss walking by......


Thanks Rob

 

Good point. I was thinking strictly mechanical.

 

my 87 has a mind of its own with the heater also. far as my research has taken me to believe that it is the logicon or the heat selector switch, nothing to do with the thermostat or radiator. mine actually alternates between vents and hot to cold and shuts it self off depending on what kinda bump in the road i hit. and a little beating on it makes a difference too.
the logicon is the heater unit with the buttons in your dash that you are resisting the urge to punch at the moment. as where the switch is im not exactly sure yet but im pretty positive its in the dash behind the logicon or behind the radio, somewhere in that area, i haven't looked at a diagram to find out yet.
so beat on you heater, or run to a junkyard and pull out a new unit.
good luck.