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Discussion Starter · #1 ·
I've been trying to look up another solution for the problem on my altima but so far nothing that's been suggested worked. Ever since I had to replace my radiator i had no heat at idle. At first I had no heat at all until I burped the coolant and replaced the lower thermostat. Now I still have no heat at idle. I've tried to burp the system again after draining it and no luck. Recently I purchased both upper and lower OEM thermostats from Nissan and replaced both of them. Is there a way for me to test for a faulty heater core without removing it? I'm going to try to flush it out tommorow but I feel like that won't change anything at this point.
 

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Discussion Starter · #3 ·
Sounds like air, try jacking the front wheels 12~15" and using a no-spill bucket. Give it some throttle while jacked and running warm, that should bleed it out.
I've tried it again and still nothing. The only time i seem to get any heat now is when I am driving 50mph+ anything less no heat blows through the vents. Could It be a leak in the head gasket maybe? I really don't want to pull out this heater core in the middle of the winter
 

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Head gasket isn't likely, and neither is the heater core if you get good heat above idle. If it isn't low coolant or air in the system then it's a flow problem, possibly a weak water pump or some sort of partial blockage in the heater loop. Check for collapsed heater hoses by feeling for soft spots with the engine off and the system cold. If you don't find anything that way, the first thing I'd suggest is a vacuum-bleed on the system to make sure there's zero air in it.
 

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Discussion Starter · #5 ·
I’ve vaccummed bleed the system but still nothing. I’m sure it’s the heater core at this point, I’ve also removed my lower thermostat to insure it was working and it’s good. To remove the heater core does the whole dash have to come out?
 

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Yep. Dashpad and console come off on the inside, cowl on the outside, then all the Main Harness connectors come loose. Then driver's seat comes loose and you drop the steering wheel on the floor. Then you can remove the steering crossmember and HVAC Unit as an assembly.
 

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Discussion Starter · #7 ·
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Yep. Dashpad and console come off on the inside, cowl on the outside, then all the Main Harness connectors come loose. Then driver's seat comes loose and you drop the steering wheel on the floor. Then you can remove the steering crossmember and HVAC Unit as an assembly.
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alright so this is where I’m at. I’ve removed the interior harness again and now I’m trying to remove this cross member. Is there any bolts under the wheel that need to come off? I’ve tried to remove all the bolts i could see but the cross member still won’t budge. Also tried to remove the old heater core without removing the HVAC but it broke instead since the HVAC is blocking the tubes from coming out. I really don’t want to remove the whole steering column to make this work
 

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Been awhile since I had a gen3 apart, but the steering wheel definitely needs to drop and I think there's a bolt underneath the cowl cover behind the wiper motor. The end bolts on a gen3 are all from the inside. The blower assembly also has to come out separately before you can pull the HVAC. Here's an exploded drawing from an '05 that should help you out.
 

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Discussion Starter · #10 ·
Been awhile since I had a gen3 apart, but the steering wheel definitely needs to drop and I think there's a bolt underneath the cowl cover behind the wiper motor. The end bolts on a gen3 are all from the inside. The blower assembly also has to come out separately before you can pull the HVAC. Here's an exploded drawing from an '05 that should help you out.
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after pushing and pulling i was able to pull the hvac out thank you. Is this bottom motor the motor to open up heat into the cabin? I pulled out the gear door assembly thing and its up right does that mean it was set to heat? I don’t really have a way to test if the motors are ACTUALLY working atm
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Yah, the upper motor with all the cams is the Mode Actuator, the lower one is the Mix Actuator. They're pretty much impossible to test with the HVAC out, but take it loose and make sure the Mix Door is moving freely and the splines on the motor and door are in good shape. Test the motor after you reinstall the HVAC, take it loose and make sure it spins when you twiddle the temperature control.
 

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Discussion Starter · #12 ·
Yah, the upper motor with all the cams is the Mode Actuator, the lower one is the Mix Actuator. They're pretty much impossible to test with the HVAC out, but take it loose and make sure the Mix Door is moving freely and the splines on the motor and door are in good shape. Test the motor after you reinstall the HVAC, take it loose and make sure it spins when you twiddle the temperature control.
Oh so the top one controls where the air goes like front lower etc? Then the bottom controls the heat or cold air?
 
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