No Heat Problem...Stumped

[240nessx]

Since I've owned my 240, I haven't had heat and I decided to finally try and tackle the problem. During the summer, I replaced the Head Gasket, Heater Core, Radiator, Radiator Cap, and the Thermostat, in hopes of fixing my no heat problem. Well come to find out, none of that fixed anything. After driving for about 45 minutes the other day I stopped and checked to see if my heater core hoses were even warm. The upper heater core hose was warm while the lower one was cold. Same with the Radiator hoses. The Upper Radiator Hose was hot to touch, while the Lower Radiator Hose was cold. I know my water pump works, because when i leave the radiator cap off i can see the coolant flowing, and it the car isnt overheating. I rebled the car for about 2hours the other day and no air came out, so im pretty sure it doesnt have any air in it. But does anyone have any ideas on what my problem could be? Thanks.

[Edwin562]

probably over cooling?? got an aftermarket temp gauge???

[Felipe2]

maybe the heater core is clogged?

[240nessx]

No im currently using the stock gauge, and it goes to the center hash mark and stays there. The radiator im using is an aftermarket oem replacement.

[240nessx]

I dont think the heater core is clogged, because i just replaced it which means absolutely nothing actually. But is there an easy way to keep that door inside the heater core inlet open? I dont think its stuck closed cause it looked like it was opening and closing when i had the dash out.

[wangan_cruiser]

blower motor

[jedi03]

using colder thermostat? or fans constantly on?

[240nessx]

stock thermostat, and it has the clutch fan.

[idahotuner]

the problem is probably under the dash,does it blow any air at all out of the vents

[Hb180sx]

inside the dash there is a white cable that controls the door that lets hot air in, make sure its attached to the temp box thing, hope that helps

[240nessx]

yea it blows air out at all times its just always cold. and the upper rad hose is 150 degrees, lower is 130 degrees and going into the heater core is 130. ill check the heater control valve tomorrow. could the car be cooling too efficiently?

[Agamemnon]

Sounds like a coolant issue.
Back flush the heater core, drain and replace coolant.

[rcdad123]

its the cabin temp control cable. like hb180sx said, check the cable that closes and opens the door under the dash. its in the fresh air duct. my heater works, but i have to hold the cable to turn it back to cold. remove the radio and check if the cable is attached properly to the climate control slider thingy. good luck.

[280zx2by2]

its the cabin temp control cable. like hb180sx said, check the cable that closes and opens the door under the dash. its in the fresh air duct. my heater works, but i have to hold the cable to turn it back to cold. remove the radio and check if the cable is attached properly to the climate control slider thingy. good luck.
Sounds like this.


If you're heater hose lines are warm and your blower unit is working then its something wrong with the hot/cold blend actuator system.

[rahjah]

I am having the same problem. My heat was kind of luke warm so I replaced the thermostat yesterday. Now, I still have luke warm or cooler heat and my temprature gauge will barely come off of cold. Any ideas?

[fliprayzin240sx]

Did you properly bleed the system? Raise the front end of the car as high as you can, take the cap off, run the car with the heater on full blast, massage the upper radiator hose until you get most of the bubbble out, keep the rad topped off and then pop the bleeder until you dont see it bubbling while still massaging the upper rad hose.

[rahjah]

We did all of those things with the exception of raising the front of the car. The coolant looked pretty bad , I think my next step may be a flush. If there is air in the system, does raising the front of the car really make that much of a difference?

[KiLLeR2001]

Most likely the cable broke off of the HVAC temp adjusting slider just like my car. In order to get heat i have to pull my bezel off and pull it manually with a pliers... Lol.

[rahjah]

If there is something wrong with that cable, that wouldn't make the temprature guage not work though...would it?

[slydin240sx]

If there is something wrong with that cable, that wouldn't make the temprature guage not work though...would it?

No it wouldn't. It would just stop you from switching between hot and cold air inside the cabin. If your temperature gauge isn't working, it might be a bad coolant temp sensor, or the gauge itself, or a thermostat issue.

I would advice getting a aftermarket temp gauge. The stock gauge is garbage!

[fliprayzin240sx]

On the fire wall side, there is a valve on the heater. You can manually open it to see if its just shut and not opening up to let the coolant thru the heater core.

[rahjah]

Since I replaced my thermostat the bottom radiatior hose is still staying cold. You guys think I may have gotten a bad thermostat off the shelf? Would it be worth replacing it with another new one and elliminating that as an issue?

[AdrenalineS14]

its the cabin temp control cable. like hb180sx said, check the cable that closes and opens the door under the dash. its in the fresh air duct. my heater works, but i have to hold the cable to turn it back to cold. remove the radio and check if the cable is attached properly to the climate control slider thingy. good luck.

ahhhhh i do i go about fixing mine on a s14 its a 95... i think my cable is stuck idk how i can break it loose i have to go inside the bay and manually open and close the stupid valve its annoying!!!!

[rahjah]

Well you are doing better than me, I can't even find the damn heater control valve on my 92 S13 hatch.

[rahjah]

Also, should my fan be running the same speed as the engine when it is idling cold? I was hoping I could rule out the fan clutch.

[Frank_Jaeger]

Since I replaced my thermostat the bottom radiatior hose is still staying cold. You guys think I may have gotten a bad thermostat off the shelf? Would it be worth replacing it with another new one and elliminating that as an issue?
I've read about people getting bad thermostats right from the store. It's worth checking. Using some tongs, put the thermostat in some boiling water, see if it opens. I don't remember what temperature it's supposed to actuate at, but you could find it with Google.

[rahjah]

Well I am happy to report that after a short period of driving, my temperature gauge is working like normal. Heat is still leaving something to be desired so I think that my next step will be a heater core back flush, new coolant and another new thermostat.