Mercury Help.

[rusty_tlc]

The heat quit in my 1999 Grand Marquise. Fan blows but the air never gets hot.
Anyody have any suggestions?

 

[sisukid1975]

is there a valve that shuts off the hot water supply from the engine to the heater core? Maybe somewhere on the firewall, close to where the lines from the engine go in....

Somtimes the linkage breaks. Or if it's vacuum actuated, there may be a leak...

Had a honda that did that, it was that valve thingy. It rusted and the cable broke off.

 

[rusty_tlc]

There is certainly a valve somewhere. Under the hood is an expanse of plastic shrouds and crap, you can't even tell there is a fire wall. The controls are all soft switchs so I assume vacuum or electric solenoid control of the valve.

 

[sisukid1975]

That valve is the first thing I'd look at... other than that, I have no frickin' clue about that car.

 

[swank60]

I concur.


Well, on the valve thing. Another issue could be a blocked heater inlet/outlet line to the heater core, or a blocked heater core. If you can find the lines leading in/out, other than having to drain the damn cooling system, it would be a fairly easy check with a water hose (and go for volume over pressure when flooding the heatercore.)


If I were you, I'd move to a nice desert-like climate where it doesn't get all that cold.

 

[rusty_tlc]

I concur.


Well, on the valve thing. Another issue could be a blocked heater inlet/outlet line to the heater core, or a blocked heater core. If you can find the lines leading in/out, other than having to drain the damn cooling system, it would be a fairly easy check with a water hose (and go for volume over pressure when flooding the heatercore.)


If I were you, I'd move to a nice desert-like climate where it doesn't get all that cold.

It was 9° F one day last week when I went to work. All desert climes are not warm.

 

[NeverFinis]

Check the coolant level?

 

[rusty_tlc]

Good idea, I'm usually pretty good about checking fluids, but there may be a leak.


I never even realized there was a special forum for non-Toy tech.

Thanks to whichever Moved this.

 

[Gumby]

Check the heater hoses at the firewall.

If one is hot and the other is cold, then you have no flow through the heater core. Blocked core or the heater valve isn't opening.

If both are hot, then the blend door isn't moving.

If neither are hot, then you are low on coolant or have a stuck open thermostat.

 

[rusty_tlc]

Check the heater hoses at the firewall.

If one is hot and the other is cold, then you have no flow through the heater core. Blocked core or the heater valve isn't opening.

If both are hot, then the blend door isn't moving.

If neither are hot, then you are low on coolant or have a stuck open thermostat.

Engine temp is normal so I don't think it's low coolant. I'll try the other check tommorow.

I found where the heater hoses connetc to the engine block and pass hrough the fire wall. The only thing that looked like a valve I could find had a wire connected, not sure if it was to sense temp or control flow though. There was another thing in the same general area as that that had a vacuum connection.
Checked the fuses on the off chance that I could go for the low fruit and an easy fix, no luck .

 

[Gumby]

The one with the vacuum connection is the valve. You might have a vacuum problem to the heater controls as well.

 

[rusty_tlc]

Both hoses get warm, the other thing with what looked like a vacuum hose connection was actually the fuel line to the injector rail.

I'm taking to a shop next week. I can't snake around behind the dash like I use to.

 

[cam75w/ls1]

Ford is notorious for he blend door motors going out so I'm sure thats it. You didn't specify if it was the regular a/c system or automatic climate control. I did a Ford truck last week that was stuck on hot and my neighbors Windstar was stuck on cold last month.

 

[rusty_tlc]

Blend door it is, 5.5 hours of labor .

I'd rather R&R my transmission and t-case in the 40 than tackel this job.

It's in the shop.