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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4508
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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Chevrolet k series: I have voltage coming into my heater

Customer Question

hi I have voltage coming into my heater relay on all terminals but nothing coming out to the heater have replaced the relay no results
Submitted: 1 year ago.
Category: Chevy
Customer: replied 1 year ago.
I have power coming from the 50 amp heater ac fuse power on the high speed from the switch power from the resistor on the right switch speed settings and the ground is grounded is it possible I got a bad relay or over looking something I should have printed off the wiring diagram before talking to you
Expert:  Jerry Newton replied 1 year ago.
Does the blower work on any speed at all?
Customer: replied 1 year ago.
no
Expert:  Jerry Newton replied 1 year ago.
You have no power coming out on the purple wire of the relay?
Expert:  Jerry Newton replied 1 year ago.
I can't make a call right now, as I am multitasking. But I can definitely guide you through this. If you use a jumper wire, remove the relay and jumper the red and purple wires, the fan should run. Does it?
Customer: replied 1 year ago.
the blower does run when jumped
Customer: replied 1 year ago.
sorry I need to go now can we continue this conversation tomorrow?
Expert:  Jerry Newton replied 1 year ago.
Of course, just let me know when you're ready tomorrow.
Customer: replied 1 year ago.
thank you
Expert:  Jerry Newton replied 1 year ago.
:)
Customer: replied 1 year ago.
Hi Im back.... So I have tried plugging in a new resistor externally with out mounting it. Also a new relay. The motor runs when it is jumped across the relay terminals. I have reduced voltage on two wires at the relay terminal from the corresponding heater switch positions. I have voltage from the heater switch high position which I believe bypasses the resistor. I have voltage on the hot wire from the 50 amp heater AC fuse. The ground at the relay is grounded although I am not sure how good. The relay switch is just not closing to provide power to the motor. What am I overlooking?
Customer: replied 1 year ago.
Is it possible that I am not getting enough amperage to the resistor or high speed setting at the relay because of burned or bad connections or bad switch? Can I jumper from the fused terminal to the high speed terminal at the relay to see if that will close the switch?
Expert:  Jerry Newton replied 1 year ago.
Bypassing the resistor like you said, this circuit should work on high. So, I think that if we solve that, we solve all of the issues. With everything plugged in and connected and with the blower turned on, backprobe these connections at the high blower relay and make sure they are still like they should be: red, orange, and purple should be hot, black wire should be grounded.
Customer: replied 1 year ago.
red and orange hot purple not black is grounded
Expert:  Jerry Newton replied 1 year ago.
Then you have a bad relay.
Customer: replied 1 year ago.
sorry I do have correction to make actually Im not able to get power on the orange when back probing with the relay plugged in with out the relay plugged in I can get reduced voltage at the orange wire on the connector
Expert:  Jerry Newton replied 1 year ago.
This means you're dropping voltage on the orange wire, which is the wire that feeds the blower switch as well. You need to work backwards from here, the problem is almost certainly further upstream from the blower switch, if not AT the blower switch, because it's affecting all speeds, not just high. Poor connection at the fuse block, defective fuse HTR/A-C, something along those lines. This is the root of your problem. Voltage measures OK when it's unplugged and no load on the circuit. One strand of wire can make a circuit test good with no load, but as soon as you try to put amperage through it, it fails and the circuit goes dead. Poor connection somewhere is responsible for this.
Customer: replied 1 year ago.
ok I will try to pull the heater switch and look at that
Expert:  Jerry Newton replied 1 year ago.
Did you get anywhere with this?