Cold air coming when the heat is on.
Mechanic's Assistant: Have you checked the coolant level? Have you checked for a leak in the radiator?
Yes and yes
Mechanic's Assistant: What is the make/model/year of your car...
Cold air coming when the heat is on.
Mechanic's Assistant: Have you checked the coolant level? Have you checked for a leak in the radiator?
Yes and yes
Mechanic's Assistant: What is the make/model/year of your car?
2009 GMC Sierra 1500
Mechanic's Assistant: Are you fixing your Sierra 1500 yourself? What have you tried so far?
I have replaced the thermostat. At High RPMs the heat works okay, then at lower RPMs it turn cold.
Read More
Responses
Nachum Wagschal
227 days ago
Automotive Expert
Good Afternoon ,
That sounds like the coolant is low and there is an air pocket .
Customer
227 days ago
It is not low. Previous to this happening, it would over heat and then rev up the engine, then it would cool down. I replaced the thermostat. It no longer over heats, but will get cold air at low rpmis this it?
Nachum Wagschal
227 days ago
Automotive Expert
both symptoms sound sounds like you are low on antifreeze. It seems like you got more coolant into it so it isn't overheating anymore but not enough to keep the heat working all of the time .
You may want to take it somewhere that can use a vacuum system to fill it to get all of the air pockets out .
Customer
227 days ago
Alright thanks.
Nachum Wagschal
227 days ago
Automotive Expert
You are welcome.
Still not sure what you need?
Have a certified mobile mechanic diagnose what's wrong with your car, at your home or office.
A small screen that is located at the bottom of the tachometer on the instrument panel is called the Driver Information Center, DIC for short. This system allows the driver to select what data is being displayed in front of...
Do you know the condition of the battery? Sometimes a battery can be so bad that it will not allow the vehicle to jump start. If the battery is known to be good the next likely culprit for your concern...
When your CD is in shuffle mode, then it will play the songs in random order. To turn on shuffle mode, press the Random/Repeat button until Disc Random is displayed. If you are listening to an MP3 or WMA disc,...
When the on-board diagnostic system picks out specific cylinders for misfires, the ignition and fuel delivery systems must be inspected. A misfire on a single cylinder may involve the spark plug or fuel injector related to that cylinder. In the...
Modern cars have the capability to adapt to the use of lower and higher octane fuels (https://www.yourmechanic.com/article/how-to-know-what-type-of-gas-to-use-by-jason-unrau), such as using 87 in a car that takes 91. E85 is different from gasoline as it is 85% ethanol and 15% gasoline....
Look under the dashboard for the alarm reset button and try and hold it in when you turn on the ignition switch. If this does not work, then try turning on the ignition the hold button in and turn off...
You didn't say which exact timing codes were set, but these codes can also be set by a faulty camshaft (https://www.yourmechanic.com/services/camshaft-position-sensor-replacement) or crankshaft sensor (https://www.yourmechanic.com/services/crankshaft-position-sensor-replacement). However, more often than not, the problem is with the timing components. The timing belt...
When it comes to across-the-board codes being set such as this, it is usually a result of something "upstream" creating the condition to set all these codes. For instance, it is rare for both O2 sensors to fail at exactly...
Hi there. It is possible that the throttle body might be the source of this problem, but also the mass air flow sensor, fuel pump relay or one of multiple ignition system components. The best way to determine what is...
Cold air coming when the heat is on. Mechanic's Assistant: Have you checked the coolant level? Have you checked for a leak in the radiator? Yes and yes Mechanic's Assistant: What is the make/model/year of your car...
Cold air coming when the heat is on. Mechanic's Assistant: Have you checked the coolant level? Have you checked for a leak in the radiator? Yes and yes Mechanic's Assistant: What is the make/model/year of your car? 2009 GMC Sierra 1500 Mechanic's Assistant: Are you fixing your Sierra 1500 yourself? What have you tried so far? I have replaced the thermostat. At High RPMs the heat works okay, then at lower RPMs it turn cold.