AC blower resistor?

[ROY SIRES]

Eric or anyone, on my 1990 Ford Festiva the ac comes on but no cold air blows out the vent ( no air at all). When switched to med and high setting the cold air comes out for a few seconds because it was working on low setting, but like I said no air blowing out the vents. On the med and high setting, just air blows out the vents, no cold air though. Does a blower motor resistor control the air conditioner too? Or is there something else that needs to be replaced? Thanks in advance

Note: The AC light comes on when switched to low, but no cold air ( or any air at all). When switched to med or high, I have air, the ac light goes off, but no cold air.

Topic

[David]

I am a little confused by your description – first for the blower, does air come out at some settings, but not others? The resistor is usually a set of resistors, and is used to step up/down the power to the blower. Depending on how Ford implemented it, if a resistor in the pack is blown, one or more than one speed will be non-functional. On most of the cars I have worked with, when there is a problem with one or more of the resistors, you can get high speed, but all the other speeds don’t work.

For the AC compressor – have you verified that the compressor is kicking on (the light is not a great indicator – you want to verify that the compressor clutch has engaged and the compressor is functioning.

If the blower works at all speeds, but the A/C doesn’t blow cold, then there could be an issue with the system – low refrigerant, failed components (pressure switch, etc.) and so on. Could also be that the evaporator is badly fouled with dust and debris, restricting airflow across the evaporator (cleaning would solve that issue, but access to the evaporator might be limited)

[ROY SIRES]

1 Yes, the ac clutch engages when on the low setting of the ac switch, but no cold air or any air at all comes out the vents on low setting
2 Air comes out the vents on med and high settings.

3 The cold air lasts for a few seconds on the med and high settings (only because the ac was working on the low setting (clutch engaged on low setting and ac indicator light was on. (low setting only) Med and high setting No ac indicator light, no cold air, but does blow air.

Also, Prestone dex-cool antifreeze, Prestone says I can use this in my 1997 Jeep wrangler Inline 6, 4.0, but take a look at the following site. https://www.consumeraffairs.com/automotive/gm_dexcool.html

Seems like Dex-cool did a lot of damage. th

[David]

So the blower is off, but the AC is on (compressor clutch engaged, compressor functioning) when the blower is in the low position

the blower is on, but the AC is off (compressor clutch disengages, compressor turns off) when the blower is in the med and high settings.

Have you pulled and checked the resistor pack to see if it’s ok, or if one or more resistors are blown? I tried finding a wiring diagram for a Festiva, but couldn’t locate one

[ROY SIRES]

You got it. I wonder if the ac fan blower resistor controls the on/off function of the air conditioner. Just thinking that if I found the resistor for it (highly unlikely) that the replacement of the resistor would not satisfy the AC going off and on. I was wondering if the resistor manufactures could make me one. If I find that wiring diagram how do I post it? Also, did you see the link I sent about Dex-cool?

[David]

Found something for a 92 Festiva – I imagine your car is similar – oddly enough, it looks like if one of the resistors blows in the resistor pack (the left one) you will be able to power the AC switch, but not power the fan, but in medium and high, you’d power the fan, but not the switch – weird.

https://www.justanswer.com/ford/4afm9-ford-festiva-1992-ford-festiva-blower-motor-not-working-no.html
Looks like you need a new resistor pack.

[ROY SIRES]

Definitely need a resistor, but there is not one to be found. I went to http://www.fordpartsgiant.com along with ebay, amazon, and junkyards etc., no such luck. Probably shouldn’t bypass the resistor by connecting via a couple of gator clips. Hope you have some luck finding Ford parts with the link above for your project car. I have to get that AC working somehow. It’s hot in Nashville, TN! Come on down and we’ll go to Tootsie’s!

[Dave]

First question I have is do all the speeds on the fan work correctly?
If all the fan speeds work correctly I don’t think the resister is at fault.
Have a look at the diagram. The ac switch is only momentary contact anyway to tell the ac head to turn the ac on. On low the circuit is grounded, on medium and hi there is a wire to the eca I am assuming is the climate control head input to have the ac on.
You could verify if this is getting grounded in medium or hi or just jumper that wire to ground and see if the ac works.
You may discover the switch is not grounding or the eca or wiring has an issue.

[ROY SIRES]

I did find a resistor on Facebook, a Festiva club group. The resistor looks like it’s in better shape than mine. Hopefully, the guy mails it to me. I will let you know if it works. If it doesn’t I will just jump the resistor like I planned on and you suggest doing. I should probably get a fire extinguisher because those things get hot. I wish I could read those wiring blueprints.

[Dave]

Could you clarify if all your speeds are working correctly.
If they are then it is not likely a resistor issue.

[ROY SIRES]

It’s in my first message. The fan did not work on the low setting but the AC light came on and the AC clutch engaged. On med and high the fan blew and the AC light went off. When I get the used resistor in from the FB guy I will send you a pic of the two.

[Author]

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