Education time yet again:-)

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On my '86 5.0 GM..........is a thermal blower lockout the same thing as a heater valve and switch?
I spliced the two wires together to get blower floor to work..............but............I was told that the reason my windshield fogs up with Prestone is due to the heater valve leaking............but there is never Prestone on the carpet, and if the valve is leaking how could the windshield fog up..........as the valve is outside of the car??

[miamibob]

Have you seen if the heater core itself leaks??

[tjc78]

Heater core time!

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Miami!
Lived in Miramar back in the 60's LOL! OK, I see no Prestone inside of the car, and I see no Prestone below the car, so how do I prove the core is in fact leaking?
And if the windshield fogs, how does it do this?

Have you seen if the heater core itself leaks??

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TJ,
My car bud who wrenches cars for almost 50 yrs in Union Beach, NJ tells me my core would leak on the outside of the car, but I see no Prestone, and the glass does fog when the car starts........I shoved strips of house A/C foam in the def ducts to stop the fogging....for now anyway:-(

Heater core time!

[sly]

pinhole leak in the heater core. you probably won't see much leak down on the floor, you'll have to pull back the carpet from the firewall to see the tiny stream. The vapor will however coat the inside of the windshield this way though. If there's no leak around the hoses to the heater core (the other possibility), then it's the heater core itself.

[gadget73]

The thermal blower lockout valve, if still installed, *might* be leaking coolant and the steam is being sucked in to the air intake. More likely the heater core is bad, but have a look at the valve for signs of leakage. I replace those with a coupler, or replace the hose and simply don't cut it for the valve.

I've had several leaky heater cores and none of them have left puddles anywhere. They didn't leak enough for that, just enough to steam the glass. When they're pissing coolant on the carpet or under the car, its a severe case and theres no doubt that its bad.

[Toploader]

Sly, no doubt that the windshield does fog and smells from Prestone.......and there is a strong smell of Prestone in the morning. Also Prestone fog seemed to me coming out of my a/c vents on the dash when the a/c was on? I will pull back the carpet to see if I see and tiny drips. Also put in new heater hoses last month............before I checked on the TBLS......now I have to yank the Plenum to get at the sucker again:-( I am in no physical position to pull the core myself.........I have a guy that does dash work very anal and clean (like me) he would be the one to do the core...........but damn I know I will be looking at $700.00 :-(

[Toploader]

The TBLS is stil there, I just bi-passed the blower so that the floor position comes on when I want it to, and not what Ford said it should:-Also what about the vac lines that attach to the TBLS...I have not touched them, they control the blend door???

The thermal blower lockout valve, if still installed, *might* be leaking coolant and the steam is being sucked in to the air intake. More likely the heater core is bad, but have a look at the valve for signs of leakage. I replace those with a coupler, or replace the hose and simply don't cut it for the valve.

I've had several leaky heater cores and none of them have left puddles anywhere. They didn't leak enough for that, just enough to steam the glass. When they're pissing coolant on the carpet or under the car, its a severe case and theres no doubt that its bad.

[gadget73]

It controls the recirc air door. If it leaks, which it usually does, the system goes to hot defrost when accelerating. Plug the lines and it'll behave itself.

[Toploader]

Had the car running today...............no leak can be seen under the pass carpet..........also no leaks anywhere near the TBLS housing. Should I still block off the two vac hoses? Can the housing itself leak, even though it is made of plastic?

I have to pull the blower motor again.........the squirrel is making noise so I have to lower it down on the shaft a bit more...........PITA!!

[gadget73]

I'd get rid of the thing just because its 25+ year old plastic in a high heat environment. It gets brittle, and one accidental bump can make them shatter. It may not be a problem today, but that doesn't mean it won't be later. When it does become a problem, its a sure bet that it will be at the least convenient possible time. Having had one of those blow out, I can tell you it empties the cooling system pretty friggin quick. From the point mine popped, it was basically dry in about 3 miles.