hvac problem

Reply Subscribe

Thread Tools

Search this Thread

Oct 12, 2012 | 02:38 PM

expydaddy

Thread Starter

Junior User

Joined: Jul 2010

Posts: 60

Likes: 0

hvac problem

Hello all. My friend showed me a problem with his 2000 mountaineer ltd, with 65k. His automatic climate control system has got the gremlins.
1) his a/c will not recharge. I think his compressor is dead but he isn't that concerned about that.
2) His automatic climate control system will not shut off. It will move from panel to defrost etc. fine. When you hit the power button to turn it off, it switches to the defrost and blows on high.
3) his heat isn't that hot.

I was thinking the blower motor resistor, but IDK.
Can anyone assist on where to look next?

Thanks in advance.

Oct 13, 2012 | 07:32 PM

shorod

Logistics Pro

Joined: Jun 2009

Posts: 4,808

Likes: 83

From: Cedar Rapids, IA

With the automatic climate control there is no blower motor resistor. The blower motor speed controller is a solid state unit, and since the blower speeds seem to work I doubt that is the issue.

There is a self test mode for the climate control. If you don't find the steps to put the climate control in self test, post back and I'll dig it up.

-Rod

Oct 17, 2012 | 12:01 AM

expydaddy

Thread Starter

Junior User

Joined: Jul 2010

Posts: 60

Likes: 0

Thanks Shorod for the response. I found instructions on running the diagnostic. No DTC's were present. I was wrong about one thing though. The fan speed is high constantly. Which, imo, narrows it to the blower motor solid state thingy behind the glovebox. Would that also fix the switching to defrost when the "off" button pushed?

I just hate to see my buddy waste money at a shop, and on a bad recommendation by me. Thanks again.

Oct 17, 2012 | 06:48 AM

shorod

Logistics Pro

Joined: Jun 2009

Posts: 4,808

Likes: 83

From: Cedar Rapids, IA

I'm not sure with the electronic controls that the blower motor will default to high speed when the speed control fails. There's no breakdown of the solid state controller to determine if there is a direct path to full speed or if it pretty much all runs through the transistor. Does the blower motor run on High all the time, or only when the climate control system is turned Off?

I doubt that the speed controller will have any effect on the switching to defrost. However, I also suspect this is correct operation as the "defrost" setting is the default as a failsafe in the event vacuum control is lost.

If it were my vehicle I didn't have access to a scan tool to control the climate control motors, etc. and I had verified the engine is providing good vacuum, I would probably start with a new blower motor speed control and see where that got me. The lack of heat could very likely be due to a low coolant level. Have either of you checked the level of the coolant yet? Have you checked the operation of the heater control valve to see if the climate controls command it to open?

-Rod

Oct 22, 2012 | 11:34 AM

expydaddy

Thread Starter

Junior User

Joined: Jul 2010

Posts: 60

Likes: 0

Thanks again for the response Shorod! Here is an update. The day after running the diagnostic he called me and said that it was no longer switching to defrost when the "off" button was pushed. It still is blowing on hi all the time though. He thinks I'm a fricking genius! I told him to enjoy it because cars don't fix themselves.

Oct 22, 2012 | 01:22 PM

shorod

Logistics Pro

Joined: Jun 2009

Posts: 4,808

Likes: 83

From: Cedar Rapids, IA

Although it is possible that the HVAC system performed a recall of the sensors when you did the self test, so it's possible that did "fix" itself for that issue. You're probably down to a bad blower motor speed controller now.

-Rod