need advice 2003 altima 2.5 no heat

[kenman1717]

Came to the shop for no heat, diagnosed bad thermostats, original. Engine has 250 000kms on it. After a day of messing around for parts, finally get new upper and lower thermostats. All back together, filled coolant, lifted front of car, and ran at 1500rpm for a few minutes and alternated with letting it idle, bled a lot of air out, topped up coolant. Heat was starting to blow out the vents, so I figured it was time to go for a drive down the highway. The heat was gradually coming back, but not at what I felt was reasonable. I've had scorching heat before after like 5 mins with the front end lifted. Anyway, was on the highway for about 10 mins, turned around and just before I got back to the shop, lost all heat that was there, just ice cold air came out. Temp gauge stayed at operating temp, and the coolant level in the radiator never went down. I'm at a loss. I could understand an air pocket if the coolant level went down, but I had some heat then nothing. This really has me frustrated. Customer was waiting for his car, now it sitting at the shop till Monday, I'm not allowed to work on Saturday. Does any one have any experience dealing with these. And I did look at some other posts about this being common. I am also in Alberta Canada and it has been between -20c and -35c the last 2 weeks.

[Stealthee]

Next thing I'd look at is the heater core.

[aleekat]

Did you have the heater on max when you bled out the air? If not, you still got air in the system.

[kenman1717]

Heater was at max the whole time. I did read in a few other Altima posts that Nissan recommends not to have it on high, and should use a lower setting. But I have never heard of any vehicle like that so I'm not sure. From experience from any cooling system repair, after the car sits for any length of time, air always seems to work it self out, so I'm going to check the level on Monday, and hopefully get somewhere with it.

I might try flushing the heater core out as well, I had the hoses off and replaced the clamps, so they should come off easy. I didn't do it on Friday, as I was -30c out and supposed to get colder over night, didn't want to leave any straight water in the heater core so it would freeze.