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Ivan, ASE Certified Master Technician
Category: Chevy
Satisfied Customers: 4871
Experience:  ASE Master Tech. 20+ years experience. 9 years self employed. Expert on AUTOLAB Radio Show
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My 2004 chevy impala heater wont heat up.Just blows cold air.

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My 2004 chevy impala heater won't heat up.Just blows cold air.
Customer: replied 8 years ago.

2004 Chevrolet impala 3.4

Already Tried:
Checked thermostat

HelloCustomer Is the temp guage reading correctly?


Your JA Expert,


Customer: replied 8 years ago.
it moves up and down from normal setting to past the 'half' way mark and back down,but to the point of over heating area,
What size engine is in your car and how many miles are on it?
Customer: replied 8 years ago.
90k and a 3.4 6 cyl

Ok, since you commented that the guage moves rapidly up and down and you have the engine and mileage that you indicated, I suspect a faulty headgasket is a strong possibility. It is very typical on these engines and is usually discovered after spending serious money trying to rectify the situation unsuccessfully. You need to confirm if exhaust gases are entering the cooling system. If they are they will displace coolant with air and very high temperaures. Once the air is introduced into the cooling system it pockets in the heatercore and causes a no heat condition. There are 2 methods for confirming this. When the vehicle is warm or running hot, the vapor emitting from the coolant bottle is sampled using a cylinder block tester. This is a cylinder that contains a blue fluid. A hand vacuum pump is used to draw the vapors through the cylinder and if exhaust gases are present, the blue fluid with change to green and then to yellow. Any change from blue at all is confirmation of exhaust gases entering the cooling system. The second method is using and emission analyzer. The exhaust probe is place above the coolant bottle and the sniffer will react to exhaust gases if present, with an increase in the hydrocarbons (HC) on the emission analyzer. This too would be confirmation. I suggest this because this is where you should start to avoid spending so much money that other spend only to find this is really where the problem was.

Customer: replied 8 years ago.
Thank you for the info.I will keep it for future use.But I found and fixed the problem,it was so simple I'm embarrassed to even mention it.
the coolant was very low,non visible in the bottle,so I added some to the full mark,let car run until gauge moved to nornal setting , turn on heater and 'instant hot air'. What a relief :).
Wife told me the car was running hot yesterday which she failed to tell me until a few minutes a go,so that led me to add coolant.
Which leads me to another question about the same car.
I am having to constantly add coolant to the refill bottle and can't not locate any leak what so ever.So where is the coolant disappearing to?
Any ideas?
That was the next thing, I was going to mention. There are 2 very common sources of coolant consumption, beside the obvious things like waterpumps, hoses, or a radiator leaking. The intake manifold gasket is absolutely the number one source of consumption. It is an item that every single 3.1 and 3.4 liter engines will have to do during it's lifetime. The second source is the headgasket issue that I mentioned earlier, except the exhaust gases are not getting into the cooling system, the coolant is sifting into to the engine and consumed. Once way to determine if the coolant is being burned, is to remove and inspect the spark plugs. If their is buildup on the spark plugs, most likely reddish, since Dexcool is orange, it is a sign. If it is on only 1 plug, I would suspect a headgasket issue. If you find it on multiple plugs, I would lean more towards the intake manifold gasket. The chances that you have an intake gasket leak probably around 90 percent. Again, before jumping in this direction, make sure the is absolutely no external leaks.
Customer: replied 8 years ago.
I'll check the plugs once the motor cools down. Thanks.
Another issue, same car
Any idea why my speedometor needle goes wacky sometimes? It will creep up and all the way over to the 120mph mark if I don't catch it in time.
What I've been having to do to reset it back down normal is to turn the ignition on and off until the needle returns to normal idle state.This is a re occuring head ache.
Any ideas?
That is most likely your instrument clutster. I just replaced the cluster in my cousins 2004 Impala SS for the same issue. This can be replaced with an exchange cluster from Chevy, You give them the vin and mileage and they will supply you a new cluster and you will give them your original one. They usually run between $250 and $350 for the part.
Customer: replied 8 years ago.
Is it easy to get to/replace,something a saturday afternoon mechanic like myself can do?

Yes, you will have no problem tackling this project yourself. Here is the procedure to remove the trim plate. Once off, just remove the 4 bolts that secure the cluster into the dash. Won't take you long at all.



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