A/C heat control panel or blower motor?

[Diego0123005]

My truck's A/C is only working in the first two speeds. After i try and run full blast on high, it shuts off. I unpluged the panel and plugged it back in just to see. Nothing changed. Blower motor still works and blows air. I am coming to the conclusion that i need a new panel. It used to work on high whenever it felt like it. Any thoughts?

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[grampadirt]

Check the blower motor resister,it controls the current going to the motor.

 

[SAATR]

The blower switch itself can be replaced, as that is likely all the problem is. Generally when a resistor fails, high will still work as it is a direct connection to system voltage. Check the contacts on the switch for continuity on each speed and you will likely have an open circuit on the faulty speed settings.

 

[LSUfan71]

Not to hi-jack the thread but his is very close to what I'm experiencing.

The blower switch itself can be replaced, as that is likely all the problem is. Generally when a resistor fails, high will still work as it is a direct connection to system voltage. Check the contacts on the switch for continuity on each speed and you will likely have an open circuit on the faulty speed settings.

My blower motor quit working. I broke the switch apart and found signs of burning & melted plastic between the Hi setting and the next lower setting. The is the second time I've found this. First time I just replaced the switch without checking anything else.

I bought another new switch and inserted it into the panel but, prior to installing the panel back into the truck, I check continuity. I found I have voltage on Hi & the next lower setting simultaneously. The problem, obviously, is that the knob, turned completely to the right, is keeping the switch between those two settings. With the switch out of the panel I can have voltage at each position without any problems. It seems the knob will not allow the switch to be rotated far enough to be placed only in the Hi position.

Questions are: Is what I'm describing actually physically possible? (allowing the switch to send voltage through both the Hi position & the next lower position simultaneously) And, if so, will this cause the melting/burning at those positions inside the switch? Looks like this is the only plausible explanation.

My solution, which I'm about to execute. Is cutting the wire from the position just below Hi, so that voltage is sent only thru the Hi position when turned fully to the right. Apparently this will leave me with only 3 positions (not a big deal)

Other obvious solutions are ordering a new $120 control panel or rummaging around Pull-A-Part, but I need a quick fix...

Note: Does not appear that I have a short between the Blower and the panel, so far...

Check the blower motor resister,it controls the current going to the motor.

Just found specific instructions on this, trying to learn more about it.

 

[LSUfan71]

Ok, answering my own questions...

With the Control Panel connected, except for the blower switch (not inserted into the knob), all 4 blower speeds work flawlessly, but with no visual indication at the switch, obviously.

With the blower switch inserted into the control knob on the Control Panel, the situation is precarious: mostly I get only the two middle speeds, occasionally three, rarely do I get Hi.

The conclusion is that the control knob has a mechanical problem that prevents it from allowing the switch to precisely align with the electronic connections for each setting.

Need new panel...

 

[LSUfan71]

Question, still, is if the control knob is allowing the switch to connect to Hi & the next lower speed simultaneously, will this cause over-hearing/melting inside the switch?

Anyone?