88 LX Interior Heating Problem, (no heat)

[usmcsgt1968]

Hey Guys,

I have replaced the thermostat with a MotorCraft RT1073, but still have no heat inside.
The radiator fans seem to be running normally. The thermoswitch has green
acid on it. Could this be effecting the switches correct operation and thus heating
the engine for normal heat inside the car? Any help appreciated.....

Thanks,
umscsgt1968

[Prafeston]

You only get heat on Defrost/Feet. Heat does not come out the dash vents.

[TominMO]

One thermoswitch is for the fan (the one in the thermostat housing), the other one, in the block, is for the temp gauge; so no, it does not affect cabin heat. If you have a nice hot radiator, then the issue is likely either the cold/heat selector slider (stuck cable) or the heater core: it's internally clogged, or blocked by external debris.

[loknlode]

criss crossed heater hoses, or clogged heater core. (thats been a problem in 2 of the festys I've had)
and in the winter I block off the front of radiator with a piece of carboard. I had to flush one rad. out
4-5 times to get all the gunk cleared out of the core. now the heat is toasty.

[FoMoCoMotion]

Heater core! Been there, done that =)

[bravekozak]

It won't hurt to Dremel wire wheel the green oxidized brass spade on the thermoswitch.

[iriegnome]

Read in another forum that you need a two-stage t-stat for the heater to work properly, which is the most common problem, but the RT is a two stage. Other than that, have you flushed the heater core? Checked to see if leaves and such are blocking it? Have you checked the radiator cap to see if it is working properly? Is your heater control valve stuck?

[TominMO]

You don't really need the two-stage t-stat. I'm using only a 180* t-stat in my B6 Festy, and the heat is adequately warm in the winter.

[usmcsgt1968]

Will check all this info out and get back to let you know what worked.....I was thinking flush time and cleaning the connection on the thermoswitch.

Thanks Guys for the Info.

[drddan]

When flushing the coolant system, use Cascade (yes, the dishwasher stuff) Cleans the system really well and doesnt hurt anything. Type "Cascade" into the search function and you can read about it.

[F3BZ]

When flushing the coolant system, use Cascade (yes, the dishwasher stuff) Cleans the system really well and doesnt hurt anything. Type "Cascade" into the search function and you can read about it.

I learn something new. even when it's old news.

[iriegnome]

I was getting no heat into my cabin of my 1992. Turned out there was no t-stat in it. Dual stage T-stats are the required t-stat. Go to whatever auto parts store and ask for a t-stat for a 1993 Mazda Miata. Works perfectly. The gasket is the same as well. Go to Walmart and pick up a Prestone Flush kit for the heater. Install that baby and flush it out. Add the proper coolant level and you should be good to go. Run that flush until everything is clear though to make sure you got everything. Flush kit is $3.44. T-stat w/gasket $11.98. Gallon of anti-freeze 50/50 $7.88.. Golden with the heat.

[sc72]

F3BZ, I learn something new. even when it's old news.

Slip over to the repair help forum, click the first sticky, Nice tidbit for those with barely any heat, proceed to page 12, scroll down to post #117 there you car read all about the Cascade powder flush and yes it works great but I would suggest you do this flush in the summer, I don't like the cold.

[bravekozak]

The purpose of the dual stage thermostat is to narrow the coolant temperature operating range. In my personal opinion, the extra expense isn't worth it. Especially, for members who live further south.

[TominMO]

You do NOT need the dual-stage t-stat! Just get the better-quality Stant 195 degree one, part #45869; $5 at Rockauto.com