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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 5789
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I'm ***** *****, the issue is 1990 gmc k2500 5.7l heater not

Customer Question

Customer: I'm ***** *****, the issue is 1990 gmc k2500 5.7l heater not working and defroster not cycling a/c pump.
JA: Thanks. Can you give me any more details about your issue?
Customer: fan works but no heat only sometimes heat will work and a/c will not turn on compressor so no a/c
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $32) to post your type of question to GM Experts (you only pay if satisfied). There are a couple customers ahead of you. Are you willing to wait a bit?
Customer: yes
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Submitted: 1 year ago.
Category: GM
Expert:  K. Wiggins replied 1 year ago.

Hello, when the heat is inoperative are both lines at the heater core warm/hot to the touch?

Do you have a multimeter available to test some things on the A/C part?