Heater/AC control

[UnderDawg]

I have a 1999 GMC Yukon. I have gone through three heater/ac controls. This fan speed selector stops working. When the control panel is removed, the wiring plug that controls the fan speed looks burnt. I replace the heater/ac control and it works for a very short time. I am getting tired of replacing the unit. What is causing the unit to malfunction? Why does the plug appear burnt? Can I prevent this in the future?

 

[GM-Tech]

Low terminal tension can result in high resistance, which results in heat that damages the terminal even more. Eventually, they'll melt the plastic part of the connector so badly that it can't even be repaired but has to be replaced. Have you ever replaced the burnt terminal(s) or do you just keep plugging in new control heads and let 'er rip?

 

We don't replace a lot of control heads on your model truck so it's not a real common problem. I'd say after three of them, you need to be looking for the real cause.

[royg]

I changed one on a 97 and didn't check the connector but when the second one went i did check it and it was burnt. I replaced the connector and wires about 6 inches down and works fine.

[UnderDawg]

Low terminal tension can result in high resistance, which results in heat that damages the terminal even more.  Eventually, they'll melt the plastic part of the connector so badly that it can't even be repaired but has to be replaced.  Have you ever replaced the burnt terminal(s) or do you just keep plugging in new control heads and let 'er rip?

 

We don't replace a lot of control heads on your model truck so it's not a real common problem.  I'd say after three of them, you need to be looking for the real cause.

 

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I just replaced the control. This time I'm going to have to replace the terminals. I don't think they will make a connection with the way they are burnt. What is the root cause?

[GM-Tech]

What is the root cause?

 

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Hard to say for sure. Maybe the current carrying capacity of the terminal(s) were a little underdesigned and if you get one that's not perfectly formed and tight, it eventually fails.

[UnderDawg]

Hard to say for sure.  Maybe the current carrying capacity of the terminal(s) were a little underdesigned and if you get one that's not perfectly formed and tight, it eventually fails.

 

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I'm going to purchase new terminals and a new control unit. Is there anything I should to do ensure a tight fight?

[GM-Tech]

  Is there anything I should to do ensure a tight fight?

 

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Not really. You could try slipping the individual terminals on the the switch itself and make sure it's a good, snug fit. That's about it.

[UnderDawg]

Not really.  You could try slipping the individual terminals on the the switch itself and make sure it's a good, snug fit.  That's about it.

 

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Thank you so much! I greatly appreciate your advice.