[Shorehunter99]

Ok recently my 97 quit blowing out heat. The fan blows but no heat just cool air maybe a lil warm after an extended time. SO i got on here and searched around and found it could be a number of things. Coolant, heater core, ect.. All those things check out fine. I check the cable and lever for the heater motor under the glove box dash and everything operated just fine. Next i check the heater control valve under the hood near the firewall. Sure enough it was in the "Shut" position so i turned it the opposite way opening it up and lo and behold hot air blew through my vents. My question is there was no cable at all running to this heater control valve. I checked everywhere around the fire wall and couldnt find a cable. Dont know if it fell off or what but i couldnt find a loose cable anywhere. I wondered if i just leave this valve in the open position if i wont have cool air but i changed my temp control to cold on the dash and then cool air blew from the vents. What am i missing? What is the purpose of this cable to control the valve and do i need it? Thanks fellas

[MR.H]

Hello, my experience on these cars is new but im sure with some more chiming in, the problem will get resolved.

If you look at the heater control valve, specifically at the piece of plastic you turned, there should be a cable that attaches to the lever, which is directly connected to the heat control slider inside the cabin. If you look inside the dash at the heater control try and see if you have a cable coming from that side, then follow it and re attach if possible, replace if not. If dont see it, then buy a new one

ill post some pics when i get home from work.

Motor side of the fire wall what it should look like with the cable attached.



And this is what it should look like on the back of the A/C control inside the cabin in the dash. The black cable is the one connected to the heater control valve in the engine bay.

[terryjai]

anyone got a picture of where the heater control valve is at on the firewall??

many thanks!

[nissanh]

Some of the colder air will run through the heater core regardless of the selection. If hot water continues to run through the heater core, if you are running AC, some of the chilled air will touch the hot heater core. Which is clearly what you don't want. IF you can stop the flow of hot water into the heater core, you will get the best AC as chilled air will not touch a hot heater core. Heater valve's job is to shut the flow of hot water to the heater core.

If you are cruising on the road, simply turn on the blower motor and get cold air from outside. If this air is warm, that means the heater core is receiving hot water!

There has to be a cable with a hook at the end. I think it is coming from the drivers side.

Just look between the rear of the engine and the fire wall.

[MR.H]

sounds like he is just missing the cable that connects to the heater control valve lever. It could be between the center console and the firewall. If you see it feed the cable back through the firewall and attach it to the lever. Hopefully the pics help

[Shorehunter99]

Thanks guys. I definitely cant find that cable going into the heater control valve anywhere in the engine bay its gone. Ill see if i can find it in the cabin around the ac control. I just bought this truck a couple weeks ago and the ac compressor needs to be replaced so the ac doesnt work. Wondering if this cable is gone as well. Thanks again.

[terryjai]

since its on the topic of heat


i think the heater core on mine is clogged.....checked everything else.....since i want to save a buck or two....have you guys ever tried to flush/unclogged the heater core with CLR or something like that???

found an post online

schematics and diagram: How to Flush Heater Core?

thanks in advance for any help

[nissanh]

Have you experienced both the hoses going in and out from the firewall is hot when the heater control valve is open?

If you want to flush, first try with fresh water without sending any chemicals into it. Just send some slightly pressurized water from the water hose that usually carry hot water out from the heater core. Remember to disconnect the other end of the hose.

[terryjai]

Originally Posted by niss:smashputer:anh

Have you experienced both the hoses going in and out from the firewall is hot when the heater control valve is open?

If you want to flush, first try with fresh water without sending any chemicals into it. Just send some slightly pressurized water from the water hose that usually carry hot water out from the heater core. Remember to disconnect the other end of the hose.

Just checked it....one hot and the other one is OK warm.....what does that mean

[terryjai]

Originally Posted by MR.H

Hello, my experience on these cars is new but im sure with some more chiming in, the problem will get resolved.

If you look at the heater control valve, specifically at the piece of plastic you turned, there should be a cable that attaches to the lever, which is directly connected to the heat control slider inside the cabin. If you look inside the dash at the heater control try and see if you have a cable coming from that side, then follow it and re attach if possible, replace if not. If dont see it, then buy a new one

ill post some pics when i get home from work.

Motor side of the fire wall what it should look like with the cable attached.

Is that at closed position aka cold air??

[gmophree]

Also interested to know if this is the open or closed position