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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3375
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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Not getting power to hvac relay switch leg it's an 05/06

Customer Question

Not getting power to hvac relay switch leg it's an 05/06 freightliner Columbia
JA: What's the make/model/year of your truck? Engine type?
Customer: It's an 05 or 06 freightliner Columbia Detroit 60 series 14 liter
JA: Are you fixing your truck yourself? What have you tried so far?
Customer: I'm a mechanic I'm fixing truck for my uncle I tested hvac relay under dash on passenger side I got 1 hot to coil on relay 1 ground to the coil on relay but I not getting power to switch leg on relay just need to know we're switch leg gets power from
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Heavy Truck Mechanic I'm going to connect you with knows all the tricks and shortcuts.
Customer: Ok thanks
JA: Anything else you want the truck mechanic to know before I connect you?
Customer: No that's all I need
Submitted: 2 months ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 2 months ago.

My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

The power comes from the 30 Amp maxi breaker.

CLICK HERE to see the relay and the power point for the pin you are referencing.

if you have power at the maxi breaker, but not the relay, then the PDM might be bad with the board inside. Usually the breaker is bad or it is tripped because the blower motor is puling too many amps and causing the breaker to remain open.


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