Defost / Dash Air blower

[ken&ellen]

On my trip back for Cape Hatteras last week the blower motors on the dash air stopped working.
I am the process of tracking down the problem and could use any tips from the group. Power, 24VDC leaves the CB and goes to a solenoid which is R-9 on drawing. The speed control is a potted device and there does not seem to be test points. We have a '91 Liberty. :confused:

[Jon Wehrenberg]

Ken, On my 87 the dash air blower failure was usually caused by a defective relay in the electric compartment under the driver's side window.

On the 87 it was the silver can type but in later models I think it changed so take this information with a grain of salt.

[ken&ellen]

Thanks Jon, That is what R 9 is, Essex ( White Rogers) solenoid, and I am in the process of locating a replacement for it. I love your salt shaker.

[Jon Wehrenberg]

If R9 is the silver can type of relay, I have bought them at NAPA, WW Grainger and Prevost. I am sure there are other places to buy one.

[BenC]

The equally common evaporator fan problem is an electronic speed controller failure. The speed controller for the dash a/c evaporator is on the passenger side dash, to the outboard of the wiper motor assembly. The dash potentiometer only sends a varied voltage signal to the controller telling it what resistance to put in-line with the motor's ground line. Of course, depending on the converter and year model, this item may require dismantling of the passenger side dash and side window closeout to gain access. The twin motors are equally as challenging (if not more so) because they are located below floor level. Checking the in and out (with a voltmeter on the scale for 24-28vdc) of the control relay will let you know if dash access is required.

[ken&ellen]

Thanks Ben, Jon was right on the money. I picked up a Cole-Hersee solenoid from Fleet-Pride and I have full functioning blowers. Now to recharge the dash A/C......I understand that the new R 134 is a new formula compatible with the R-12 system once the R-12 is removed. Ken

[truk4u]

Ken,

They are not compatible because of hoses! You will hear everything from it's ok to it's an $8,000.00 conversion from Prevost. My advice like I have done, go on Craigslist and find a 30 lb tank of R-12 and stick with it. I have bought 2 virgin sealed tanks locally, one for 200.00 and the other for 250.00. Here's one on Craigslist today: http://atlanta.craigslist.org/wat/pts/1842131554.html

The compressor and dryers are cheap and R-12 does a great job. Do a search for R-12 here and you'll find plenty of information.