2001 Windstar Rear Auxiliary unity not blowing air

[5greenmonkies]

2001 Ford Windstar rear auxiliary unit will not blow hot or cold air.The front system works fine with very cold or very hot air as needed.The system has been in this state for the past four years.Last month I had a local shop evacuate the refrigerant and then I replaced the following A/C components (compressor, front orifice tube, rear expansion valve, receiver dryer, and condenser). The shop then recharged the system and the front blows ice cold air...amazing! Unfortunately the rear system just doesn't want to blow any air, hot or cold. To date I have completed the following checks:

Relays
· Front cabin relays #3 and #6 were swapped with no change to front system.
· Rear unit relays make a clicking sound when either front or rear control panels set blower motor speed.
o I swapped out with front and rear cabin blower motor relays with no change to front blower motor.
· Engine Compartment – Both 40A fuses were checked (117 & 120).They are supposed to be 40A fuses but my box had 50A in both places.It had been like this for years with both systems working fine up until the rear unit ceased working.(NOTE: maybe this is coincidence but when I changed these from 50A to 40A my son noticed that some of the rear tail lights stopped working…in fact all of them associated with fuse #7 located in the passenger cabin.)

Fuses – all related fuses were checked and are fine.As noted above the distribution box fuses were changed from 50A to 40A with no detrimental effect on the front system working.

Front Control Panel
· Heat and air work fine (blower and temp controls)
· Front control panel appears to change rear unit temperature setting but only one of blend door actuators adjust when changing temperature setting
o The one closest to the blower motor does not function.The one that directs air to floor or ceiling functions properly.
o Shouldn’t they move together based on the temp setting?
· Front control panel blower motor settings only result in hearing a clicking noise for each setting.
· Setting front control panel to REAR CTRL allows rear control panel to function.

Rear Control Panel
· Temperature settings - same result as front control panel with blend door actuators.
· Blower motor settings - same result as front control panel.

Rear Auxiliary Unit
· Expansion valve makes a hissing sound on A/C or Defrost settings.
· Blower motor was removed and benched tested for operation.
o Electrical connection looks fine and seats snug.

Any and all recommendations will be appreciated.

[tomj76]

I have a '96 and it seems like your rear heating/ac system is different. I don't have temperature control, instead there are discrete blower settings, then one that gives control to the rear passenger. Also, the heat/cool control is a single vacuum motor run by the fan control.. CCW positions move the blend door to make cool air, CW positions move the door to make hot air. The change from hot air to cold is not gradual, it's either one or the other.

If I were looking to cure your problem (inactive fan motor) in my system, then I'd start by checking for B+ power at the fan motor, the front dash board control, and the rear dashboard control.

Also, I had a failure of the vacuum switch in the front dash control, and I'd get hot air from the rear system regardless of the position of the dash control.

[5greenmonkies]

tomj76 - Thank you for your reply. I think our systems are pretty similar from your description. I took photos of my system components to post but the images are too large even after compressing them. Anyway, what is B+ power and how do I measure it?

[tomj76]

B+ is another name for the battery voltage, usually ~12 V dc. It should be present on any wire that supplies power to a device. For example, when the fan motor is turned on one of the terminals should be connected to the body (and ultimately the battery negative terminal) and the other should be connected the battery positive voltage (B+) or ~12 volts.

You can test for it with a volt meter (e.g. DVM) or a test lamp.

[5greenmonkies]

Got it, thx. I will working on it this weekend.

[5greenmonkies]

My weekend became consumed by activities beyond my control but I was able to find a few minutes to check the volt reading (B+) at the rear blower motor connection. With the van running and the rear blower motor set to high, from the front control panel, I heard the typical clicking sound but had a reading of zero volts at the blower motor connection.

I also pulled my tire jack mount and located the rear electronic module. The ground seems fine. No corrosion noted and a solid attachment.

Help!!!!

[tomj76]

That's a good first step. Now to find out why. I don't have schematics for a 2001. In my 1996 the rear blower is probably powered directly from the front speed control, but also through the rear speed control when the front knob is set to allow rear control. If there is never any voltage (rear or front control positions), then I'd bet the power isn't making it to the front control.

I'd be surprised to find out that the blower is powered through the rear electronic control module. (There is no rear electronic module in the '96) However, you can find out by using an ohm meter to check for low resistance between the rear module connector and the blower. You don't know which pin, but it has to be one of the ones with no voltage.

[tomj76]

As I think about this problem a bit more, it is also possible that the wiring at the motor is at fault. First check the ground connection and make sure there is very little resistance to the body of the vehicle (<1 ohm), which is sometimes hard to do since the body is painted. If that checks out, then find out where the motor positive voltage wire comes from, and check for low resistance to the motor. If both check out, then you'll need to either keep checking points closer to the battery, or starting from the battery, closer to the motor. Once you know where the power is getting stopped you can find out why.

[12Ounce]

Do you have a Ford electrical diagram book for your model?

[5greenmonkies]

tomj76 - thank you for your troubleshooting. I've been beaten by rain these past few days (working outside) but hoping for sunshine over the holiday weekend. More to follow.

[5greenmonkies]

Originally Posted by 12Ounce

Do you have a Ford electrical diagram book for your model?

12Ounce - I only have a Haynes manual which is pretty much worthless.

[tomj76]

For a small fee you can get temporary access to the full set of Ford Service manuals (on-line) for your model. I've used it for some repairs when I didn't have good manual coverage. It costs ~$20 for one month access, but you can purchase a shorter or longer time. Go to http://www.motorcraftservice.com/vdi...=productdetail

Also, check E-bay for the wiring manual. I picked one up for a small reasonable price.

[12Ounce]

If you have the manual, " ...all will be revealed"! They are well laid out ... easy to follow. I prefer the paper one ... but that's me.

[scubacat]

Originally Posted by 5greenmonkies

12Ounce - I only have a Haynes manual which is pretty much worthless.

PM me your email address and I'll send you what you need. (Email me TODAY or you may have to wait a while..)

Did you check the blower motor resistor? It usually fails and removes the lower speeds but it's possible that it's blocking connectivity.

[5greenmonkies]

Subacat, 12Ounce, tomj76,

Thank you all for your assistance. I've been out of pocket and will be for another week or so. Subacat, I PMd you...thank you for the offer.