I have a 2003 maxima, 85k miles. I replaced the radiator today because it began to leak around the joint at the top plastic tank. Job was easy and went well. I allowed it to run for a while to make sure there were no leaks. I noticed it was blowing cold air instead of heat. I thought maybe there was an air bubble somewhere but the coolant is hot meaning it is circulating. I drove it and it began to blow heat but then when I stopped it blows cold again. Can someone tell me what is wrong and causing this and what to do to fix this??!! Thanks in advance for your help!

 

The cooling system is probably low on coolant. When you fill the radiator on level ground, not all the air comes out. You need to raise the front end up (a foot would be more than enough). You could also have the car parked on an uphill incline. With the radiator cap off, run the engine until the thermostat opens up and allows the trapped air to escape. Don't be looking into the radiator when the air comes out, it tends to spit a little bit of coolant out.

If you aren't in a hurry now that the car is together, park it with the front end up and let it cool off. Make sure the overflow tank has some extra coolant in it. When the car is cold, remove the radiator cap and the radiator will probably appear empty. Fill to the top with coolant, replace the radiator cap, top off the overflow tank and drive the car. Depending on how much air is trapped, you may have to do this a 2nd time.

 

Just because the coolant is hot doesn't necessarily mean you don't have an air lock. Try leaving the cap off the rad and running the car at idle until it gets hot and see if there are any bubbles or if you have a bleeder screw remove it and bleed the air out and if that doesn't do it your thermostat may be sticking and need to be changed.

 

I filled it while it was still on the ramps about a foot high. Tomorrow morning I will open the cap before I start the car and see if it appears low.


Thanks for the suggestion.

 

There are a ton of threads on here with the proper procedure. Essentially, you need get it to op temp, fill, let it cool, fill more and do it several times until it isn't low. Squeeze hose with elbow on drivers side to get air out of there.

 

I have been doing that and it is getting better, the first couple times when I took the cap off it burped some air. Thanks for the reply.

 

thats just air making its way to the highest point of the system which is the radiator. when you bleed the system, you need to hold it around 2000-2500rpm. while the system bleeds, keep topping off the rad. when the thermostat opens and the water gauge needle is half way, almost if not all the air should be out of the system. dummy proof way is it should be done bleeding when the electric rad fans come on