How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 29583
Experience:  GM Grand Master Technician 2007. 14 years experience.
10949255
Type Your Pontiac Question Here...
GM Tech (Cam) is online now
A new question is answered every 9 seconds

Pontiac Grand Prix heater not working; replaced thermostat

Resolved Question:

I own a 2008 Grand Prix and it has no heat, changed the t-stat, it isn't over heating; gauge is between 1/4 and 1/2, still no heat.

Submitted: 5 years ago.
Category: Pontiac
Expert:  GM Tech (Cam) replied 5 years ago.

Hello. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.

Are the heater hoses to the heater core hot when you touch them?

JACUSTOMER-8dx3rr23- :
i have no heat, changed the t stat
blows cold air

GM Tech (Cam) :
OK so we need to see first if there is hot water getting into the heater core or not so we need to see if the heater hoses, both are hot.

JACUSTOMER-8dx3rr23- :
one hose is hot

GM Tech (Cam) :
and the other?

JACUSTOMER-8dx3rr23- :
warm to the touch

GM Tech (Cam) :
but significantly colder?

JACUSTOMER-8dx3rr23- :
yes... are these cars know for the heater core to plug up

GM Tech (Cam) :
Ok, easy place to try next, take those lines off the heater core and spray water from a pressure washer into the port that was the colder line first. Flush both ways and see what that does.

This will clear a blockage and the high pressure creates enough turbulence to get the coating off the inside of the heater core from the coolant.

JACUSTOMER-8dx3rr23- :
will try that, are these cars known for the heater core plugging up

GM Tech (Cam) :
yes they are.

JACUSTOMER-8dx3rr23- :
so i should put a new one in

GM Tech (Cam) :
No, try flushing first, much cheaper!!!!

JACUSTOMER-8dx3rr23- :
with new coolant

GM Tech (Cam) :
IF it works then do a whole coolant flush.

JACUSTOMER-8dx3rr23- :
ok will try that

GM Tech (Cam) :
If that does not help then we could be looking at the actuators that move the heater doors.

JACUSTOMER-8dx3rr23- :
but that don't stop the coolant flow?

GM Tech (Cam) :
The actuators stop the air flow through the core, not coolant flow.

JACUSTOMER-8dx3rr23- :
will try the flush first cause one hose is cold

GM Tech (Cam) :
That is the logical place to start.

JACUSTOMER-8dx3rr23- :
if not i will be back

GM Tech (Cam) :
Absolutely!!

JACUSTOMER-8dx3rr23- :
thanks for the info

GM Tech (Cam) :
MY pleasure.

GM Tech (Cam) and 5 other Pontiac Specialists are ready to help you