there's no heat AC system

[fabrizio]

Hi!
The AC system does not heat , setting the temp to max it still blowing cold air.
When i run the auto diagnostic DATC,
the displays turn on all his digits , there no count down or any error message .
Just some noises from the air inlets closing.
No fan noise.
after some minutes , pressing any button the display turn off.
It works fine with cold air ,some times does the "jet noise".
Blower speed works Ok.

heat valve issue ?
where should i start ?
lincoln ls v8 2001.

Best regards!

 

[joegr]

http://www.lincolnvscadillac.com/fo...wing-Diffrent-Temp-out-of-diffrent-vents-HELP

(Just one of many many threads to look at for this...)

 

[fabrizio]

Checking the datc connector I saw an extra wire soldered directly to pcb board.
The wire looks like routed to the valve.

Maybe this does not allow the vavle to work as it should.

How the valves work ?
Normally open or close ???

Best regards!!!

 

[joegr]

It's likely that is a bad repair attempt that someone made.

The DCCV is two 12V solenoid valves. In their unpowered state, both valves are fully open (full heat). They are powered to close them (no heat). When power is removed, they automatically open due to a spring inside. The DATC PWMs (pulses) them to get settings between full heat and no heat. The DATC supplies +12V to the common wire to the valves the whole time the system is on. To close the valves (reduced or no heat), it switches ground on and off to the other two wires (one for the driver's side, and one for the passenger side). The driver's side heater core is larger than the passenger side one, so it has a bigger effect on air temp than the passenger side one.

 

[LS4me]

Shouldn't one suspect the thermostat in this situation?

 

[joegr]

Shouldn't one suspect the thermostat in this situation?

You can, but even wide open you should get some heat. Also, you would see a low reading on the temperature gauge and might even trigger a check engine light.

Other suspects are:
1. Trapped air in the system preventing liquid circulation in the heat loop. This would most likely be due to micro cracks in the plastic cooling parts letting air in.
2. Failed and clogged aux pump.
3. Clogged screen in upper radiator hose.
4. Clogged DCCV.

Clogs shouldn't be an issue if the cooling system is flushed every three to five years and premixed coolant is used (or distilled water is used to mix with anti-freeze).

 

[fabrizio]

Ty for reply.
I'll measure the voltage on wire and try to test the solenoid.

Then i'll do the "suspects"

Thank you!

 

[1LoudLS]

Shouldn't one suspect the thermostat in this situation?

from my experience, with a thermostat failure you would either get no heat at all (failed closed) BUT the car would be severely overheating all the time, or (if it failed open) you should get some heat once the car reached operating temps BUT you should have the symptom of the car taking forever (if it even does) to get up to that operating temperature. so I would expect to see one of these other symptoms before thinking it was the Tstat(which maybe he has but didn't mention them).

 

[milehighmikey]

My DCCV (heater valve) failed shut recently and replacing it was totally the correct repair.

Am I the only one who wonders why no heat is a problem in Mexico? ;-) Times must be tough! I know that in NH they sure are! -11F this morning. As Charles Barkley would say, "It's trrrrbul."

Good luck with your repair, Sr!

 

[1LoudLS]

hey man, even the desert can get quite cold at night!

 

[shake the cove]

I have to replace my DCCV this weekend. My factory manual says to "disconnect the quick-couple disconnect hoses" Is there a trick to it or do need a special tool ,like when disassembling fuel lines. Unfortunately I will be outside with the job this weekend temp 45* ?rain /drizzle.[ Garage occupied by pontoon boat with no trailer to pull it out] I would like to spend as little time out there as possible.

 

[joegr]

Maybe this? http://shop.advanceautoparts.com/p/otc-chrysler-ford-heater-hose-disconnect-tool-otc7413/17632136-P

I didn't have to disconnect the hoses at that end on my gen II V8, only at the DCCV end.

 

[milehighmikey]

The quick disconnects use a ford special tool and they are destructively used. you need new ones when you put it back on. They are fairly expensive, as I found them to be around $8 each so you'd need 3. I kept mine in one piece and opted for the hose clamps at the valve itself, no party at all to get to and release.