# No Heat



## 451stroker (Jan 22, 2017)

Hello,

I'm working on a 2008 Rogue that has almost no heat. The thermostats have been replaced. I've bled the system of air. When it reaches operating temperature, the lower radiator hose is cold, and the upper hose is hot. After about an hour of running, the lower hose finally gets hot and the heat is acceptable. So basically, there's no heat for any around town trips. You have to drive the car for almost an hour to get heat.

Does anyone know why the lower hose is cold and the upper hose is hot when the gauge indicates that the engine is at operating temperature? The system has been bled more than once, and the fact that the lower hose eventually gets hot and I get heat after an hour makes me pretty sure that there is no air in the system.

Also, why are there 2 thermostats? Is it possible that the lower thermostat is taking too long to open and that's why the lower hose is cold? Before I got the car, a service station replaced both thermostats in an attempt to fix the problem, so I doubt that the new ones are faulty. Would removing the lower thermostat solve the problem, or cause new ones?

Any help would be greatly appreciated.

Thanks!


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## Car guy (Mar 31, 2016)

There are 2 thermostats: one for the block and one for the block/head. The block one is called the water control valve and has a higher opening temp than the thermostat. I think 203' and 180', respectively, or thereabouts. The lower radiator hose can be cold if the outside temps are COLD, below freezing, even if the dash is showing normal operating temp range. Still, there should be hot coolant flowing into the cabin. If you check (feel with your hands) both of your firewall heater hoses, are they hot? What is the level of your coolant reservoir when the engine is COLD (off overnight)? Perhaps your cabin air duct valve is not opening allowing the hot heater hoses' coolant to flow. Also, what part #s did the service station install for both thermostats? Did the station replace the radiator pressure cap?


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## 451stroker (Jan 22, 2017)

The heater hoses don't get hot until the lower hose gets hot (which can take more than a half hour). I'm not sure of the thermostat part numbers the shop used, but they replaced them in an attempt to fix the same problem, so it was definitely occurring before they were replaced. We just replaced the radiator cap with a Stant one last week, but the problem continued. 

What is the cabin air duct valve? Is that the blend door?

Thanks!


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## Car guy (Mar 31, 2016)

Not having the answers to the other questions ...

If one (or both) thermostat(s) originally were stuck open 
AND actually not replaced 
OR replaced with defective slightly open 
OR they buggered the o-ring seal(s) when they did replace, allowing seepage throughput
OR they put the thermostat where the WVC goes and vice versa, effectively jamming the housing on the end of the thermostat causing the spring to be compressed allowing coolant throughput
then ...


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## quadraria10 (Jul 6, 2010)

CarGuy is right there is no guaranty the previous mechanic did a proper job and/or installed quality parts. Maybe you need to bleed the system again?


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## 451stroker (Jan 22, 2017)

I just have no way of knowing without taking the T Stats out. I would think the lower T-Stat is definitely staying closed for a while though as evidenced by the cold lower hose. Regardless, shouldn't the water pump be circulating coolant through the heater hoses?


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## Car guy (Mar 31, 2016)

Can you see new liquid gasket at the thermostat cover?

Can you spot a new actual gasket at the WCV housing (or liquid gasket if they used that instead there)?

On your question, yes; the evidence suggests it is circulating.


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