98 Windstar blowing hot air in rear a/c

[Lbert]

Chad, sorry. I am not much help from here. Perhaps someone else can help you out.

[chad1971]

Thanks for all your help!!!

[tomj76]

If the air is coming out the roof vent, the your problem is probably not caused by misdirected air flow.

The rear heat has a vacuum motor (controlled by the selector switch) that will direct air through a heater core or through an A/C evaporator. A spring in the vacuum motor forces the vents to direct the air through the heater when there is no vacuum applied. When the air is directed through the heater, it exits the floor vents. When vacuum is applied to the motor, the air flow changes so that it passes through the evaporator and exits from the ceiling vents. When the selector switch is set to vent (no A/C) the air also passes through the evaporator, but since the A/C is off, there is no cooling of that air. I don't believe there is any way to have some air pass through the heater core and some around it.

Since your air is coming from the ceiling vents, I suspect that your selector switch is fine, and the vacuum motor is working correctly. Since that air is not cold as it should be, my guess is that the problem is with your A/C unit. If the front vents are giving cold air, then my first guess is that expansion valve in the A/C evaporator is not working right.

You can make a quick check by feeling the pipes that bring refrigerant to the rear unit from underneath the van. With the van idling and the A/C on max, and the van safely in Park, the parking brake set, wheel choked to prevent any unexpected movement of the van (we don't want you be be run over!!), look just behind the driver seat from under the van and you will see two metal pipes. One will be hot and the other will be cold if your rear A/C is operating correctly. If both are hot, then the expansion valve is wide open. If they are neither hot or cold, the valve is probably totally closed (although I'm not sure that's possible).

If you are also not getting cold air from the front vents, then you've had a general failure of the A/C, which could be due to a number of causes from a leak to a failed compressor.

[milo42gpw]

An additional FYI, My 98 also blew hot air in the back. I found that the vacuum line was deteriorated and and not able to pull a vacuum on the valve. I bought a new hose at Advance Auto for a few bucks and spliced in the new line. The line in directly under the selector area on the outside bottom of the van.

[chad1971]

is that vaccuum line going to the back??? My rear unit looks like it is all electronic with no vaccuum lines in the back, I'll double check. Thank you!

[onit]

If i remember correctly the floor vent in the second row seats is for the rear heat if you have that option. I have both the rear a/c and heat and when i put on the heat in the winter it comes out the floor vent. When i put the rear a/c in the summer it comes out the roof and side vents in the second row where there is also a fan speed control.

[tomj76]

In the '96 (with the rear A/C option) there is a green vacuum hose that enters the rear unit (just behind the driver seat) that originates in the dash at the heater controls.

[chad1971]

Thank you!!! I will try this when I get some time...

[weisguy34]

Thanks to everyone for their help on this subject. Back seats are now chillin' since changing the blower switch in the front a/c console in about 30 minutes.

For anyone else that stumbles across this posting with this problem and is looking for OE or aftermarket replacement blower switch in front, below is a list of part numbers I found in my research, along with their quoted retail price.

Ford/Motorcraft: F68H19A642AA, YH1465, & F68Z19986AA $53.98
NAPA: TEM 207993 $31.87 (Napa cross referenced this from Ford no. photo does not look exactly correct so be sure to double check this when buying)
Autozone: SW3320 $40.99
Carquest: 53-12136 $28.00

I ordered from Carquest, had it in 2 days, and was the exact same switch as the one that was removed, even down to the Motorcraft number stamped into it. Item was special order at all above local locations, so may have to pay freight if is the same situation in your area. I did not try the Ford Dealer in WA that is mentioned in the above thread, so that also remains a possibility. Hope this helps!

One last thing - never forget your local salvage yards either - most have plenty of late 90's Windstars to choose from.

[SGT-Topo]

hldurham ref your post 06-01-2007, 09:19 AM - I had the same issue and found your post to be very helpful. Thanks.



eciessau ref your post 06-10-2007, 04:49 PM -this tip really helped me troubleshoot and BTW all I did was gently pull the plug from the rear switch; the one with the black and white vacuum hoses. Than I plugged the black line with a small nail and like you wrote "PRESTO--front air comes out of vents!!!" I just installed the new switch and both are working fine now.

Thanks :-)

[njlion]

Having somewhat of a different problem. 2003 Windstar. No air coming out of the dashboard vents, but blows out of the defroster vents and floor vents, hot air when heater is on, cold when a/c. Is problem with this same switch?

[tomj76]

The front air is controlled only by the switch that selects the heating mode, and by the hot/cold adjustment.

The hot/cold adjustment controls a servo motor that allows some air to pass through the heater core after it has gone through the evaporator. The mode selector control another motor that directs it to the desired exit point, (i.e defrost ports, dash board vents, or floor vents). Hot air that's coming from the expected vents implies that there is a problem with the hot/cold adjustment control, either at the knob or at the servo motor.

[Freakzilla69]

Something to check:

I had this problem, changed the dash selector switch and it didn't fix it. I followed the vacuum lines from the switch and low and behold...

there is a big white connector behind the dash, it had come undone, someone's foot must have gotten caught on it. It can be reached from underneath the dash.

Make sure you're getting a good vacuum from the engine, too.