# No cabin heat + air pockets.. why?



## ommynous (Aug 23, 2016)

Thanks to all who read and offer an opinion. Winter is coming, and I would not like to be cold like I was last winter.

Anywho, this is all I know about the car. An '02 Sentra GXE

The coolant system is getting air pockets, according to my mother, who the previous owner of the car is. It so apparently had a head gasket issue, as well. We treated it with Blue Devil, and the results were satisfactory. Minus the clogging of the radiator. From what my mom has told me, and what her mechanic said to her, gutting the thermostat was the apparent solution to the air pockets. Doing so allows the cabin heat. Before investigating further, I just replaced the thermostat, and the radiator. I didn't do a system flush, cause the drained coolant looked clean. I manually remove the expansion tank and clean it.

Fast forward an hour or two. After cranking up the car and letting it get to temp, I realize 2 things. 1: I have no cabin heat after replacing the thermostat. 2. my temp gauge isn't giving me a reading AT ALL. I've also had issues with that. My temp gauge only gives me a reading half the time, and when it does, it shows my engine getting to operating temp, and slowly declining - along with my cabin heat - seeing as it's getting colder weather, this made sense to me.

What am I missing? Is this ECTS tied in with the Heater core somehow? I don't have any coolant leaks that I'm aware of.


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## rogoman (Dec 16, 2004)

Did you replace the thermostat with a Nissan OEM thermostat or an aftermarket type; aftermarket stats many times cause more problems. When installing the stat, make sure the jiggle valve on the stat is at the top. Also make the radiator cap is OK. Did you purge the coolant system of air? Here's a procedure for purging air:

You will need a funnel that fits snugly in the radiator neck.
Fill it half way with coolant.
Raise front of vehicle up as high as possible. The idea is to get the radiator above the engine.
Start engine and turn heater to hot and blower on high.
Repeatedly squeeze the upper and lower radiator hoses to get air to bleed, you will see bubbles coming out of the funnel. This is the air escaping. Keep doing this until no more air comes out.
Reving the engine to 1500 rpm should help this process as well.
Once you get the heater to blow hot air while at idle speed your done.
Lower the vehicle and leave the funnel in the radiator, fill the radiator up at least half way.
Let the engine cool down. As it cools the any left over air pockets will contract and cause more coolant to be pulled in.
When engine has cooled remove funnel and install cap.
Top off reservoir to proper level.

If the engine in your car is a QR25DE, there are two thermostats; the regular one on the side of the engine and the second one on the back of the engine called a water control valve. The main purpose of the water control valve is to allow the engine to warm up faster from a cold start.


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## ommynous (Aug 23, 2016)

I haven't tried bleeding the air out that way. Will give it a go soon. Also, the original thermostat that was gutted was OE, with a replacement from rock auto. I'll get the brand when I get home. But it said it was OE spec. But after the old one was gutted, the cabin heat returned. Why would it cause that?

Is it possible that blue devil clogged my heater core?


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## ommynous (Aug 23, 2016)

SOLVED!... Partially. I checked for where the inlet and outlet hose would be, going to the heater core. Sure enough, one was thick and cold, the other was hot and squishy. Squeezing it didn't seem to let out any air, or help it any. I'm gonna replace the heater core. I know that's a VERY tedious job... Will post the results later.

It does seem that the use of blue devil has clogged my heater core. I would caution anyone further using this product. If they can do the head gasket repair themselves, just do it and get it over with. Or else you'll be doing a butt load of work cleaning up the mess it makes. Maybe we just used too much of the product. Who knows.


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