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gamellott

Heater Issue...

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Sadly, it's been a hot minute since I've been here. I notice some things have changed 😁

 

On my 92' WD21, the heat stopped working. Everything else works fine. It's the electronically controlled version and I can't seem to find a thread that covers the topic very well. I'm sure this problem has been addressed before, but I can't find it... 😭 I'm assuming there is some kind of valve that controlls the water flow; where is that and is it very difficult to get to? The last time I had to replace a heater control valve was in an 81' 210, 25 years ago... This is not the same animal 🙄

 

 

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I have the semi-automatic HVAC system in my 93. It doesn't have a control valve for the heat like my old Datsuns had. The temp is controlled with an air mix door in the HVAC box. For hot, the air is run through the core and cool it is bypassed around the heater core. 

 

I suggest that with the engine warmed up, feel the 2 heater hoses and see if they are about the same temp. If one is noticably cooler than the other, it is a good indicator that the core is clogged. Sometimes you can do a reverse flush on the core by detaching the hoses and hooking up a garden hose to the outlet of the heater core and letting the water flow until it is clear.

 

If you gave good flow through the core, the servo or the air blend door is likely bad. Most often it is the servo that operates the door that fails. 

Edited by Mr_Reverse

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Lol, years ago I had an 80.5 210. It was the sport version, 2 door hatchback with the 5 speed and the big engine, the mighty 1.4L OHV. Good times, that car hated me, but loved my wife at the time. She kept wrecking it, but always started and ran for her. With me, not so much. Did like the 28 mpg City and I could pass the speed traps at 80 in the 55 mph days and be completely invisible to the police. Guess they thought that little wreck couldn't really go that fast and ignored what the radar would tell them. 

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I keep wondering when mine's gonna do something like that. The HA section of the '95 service manual (you can download the whole thing here if you haven't yet) has troubleshooting for the auto HVAC starting on HA-55. Scroll down a bit and there are diagrams of the circuits and where everything's hidden. Unfortunately I'm not seeing much about heat in there, but it might help you figure out what you're looking at, anyway.

 

As for easy to get to, I tried to open up my HVAC box apart when I had my dash out, and found that the piping for the evaporator was not going to let it come out unless I discharged the system and unhooked the lines (which I didn't want to do at the time). There may be a trick to it that I don't know, but I screwed around with it for a while and succeeded only in screwing up the foam seal between the case halves. Looks like the actuators are on the outside of the box, so if that's what's gone out, hopefully it's not too difficult to get into. I opened up one of the servos in mine when I had the dash out, just to see what it looked like inside, and it looked fairly straightforward; you might get away with just cleaning/bending some wipers depending on what's worn out.

I keep threatening to convert mine to the cable setup, but that project's pretty low on my list right now.

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Thanks guys, You're always a great source for information and I appreciate it!!

 

Not entirely off topic, but I was having an issue with my coolant not going back into the radiator when it cools down and I believe I have it fixed. The heat would go away when the radiator was low, so I thought it could have been that. Orrr... Maybe it's the actuator for the door just being intermittent. I work with electronics and know that old electronics become flaky as many of the electronics on the Pathy are becoming that way. Too many problems and not enough time to play and fix...

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11 hours ago, Slartibartfast said:

I keep wondering when mine's gonna do something like that. The HA section of the '95 service manual (you can download the whole thing here if you haven't yet) has troubleshooting for the auto HVAC starting on HA-55. Scroll down a bit and there are diagrams of the circuits and where everything's hidden. Unfortunately I'm not seeing much about heat in there, but it might help you figure out what you're looking at, anyway.

 

As for easy to get to, I tried to open up my HVAC box apart when I had my dash out, and found that the piping for the evaporator was not going to let it come out unless I discharged the system and unhooked the lines (which I didn't want to do at the time). There may be a trick to it that I don't know, but I screwed around with it for a while and succeeded only in screwing up the foam seal between the case halves. Looks like the actuators are on the outside of the box, so if that's what's gone out, hopefully it's not too difficult to get into. I opened up one of the servos in mine when I had the dash out, just to see what it looked like inside, and it looked fairly straightforward; you might get away with just cleaning/bending some wipers depending on what's worn out.

I keep threatening to convert mine to the cable setup, but that project's pretty low on my list right now.

That's some really good information, hard to figure it out though. Wish it was more "year" specific though.

 

You guys wouldn't happen to have the resources to actual electronic/schematic drawings with specifications on resistors, capacitors and other random components, would you?? I have a few things that I might want to rebuild.... since some of my stuff has become... glitchy... The resistors, in my experience, tend to be the high failure components and tend to go out of tollerance and are usually the culprit. But like anything else, the drawings for those are hard to come by.

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The not pulling coolant back from the overflow bottle back into the radiator is usually a failed radiator cap. If not that, there is a leak in the hose. 

 

The door actuators on the HVAC system are all externally mounted and are just simple motors with reduction gears. The gears tend to break when old preventing operation. 

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On 5/16/2019 at 8:21 PM, Mr_Reverse said:

The not pulling coolant back from the overflow bottle back into the radiator is usually a failed radiator cap. If not that, there is a leak in the hose. 

 

The door actuators on the HVAC system are all externally mounted and are just simple motors with reduction gears. The gears tend to break when old preventing operation. 

 

I had replaced the radiator, it was the original and leaking all around the seams and the cap was brand new, so I looked elsewhere... I found that the hose within the tank was just barely hanging on to the tube, so I threw some lockwire around it in order to seal the hose in place. Since it's not my daily driver now that its warmed up a bit, I haven't been keeping an eye on it.

 

If it continues with intermittent heat, I'll have a look into those motors. Are the gears available for replacement somewhere? Napa and Rockauto shows squat for parts available, or I'm looking under the wrong rock. 

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Sooo.... After looking at the illustrations that Nissan provides, I don't know exactly which part it is that I'm looking for, but it doesn't look like there are any parts available for this anyway. I'm under the impression that if the mixing door motor is failing, I might simply have to convert it over to manual, or figure some other way to skin a cat... Start stalking the local boneyards... Because WE NEED a heater in WA....

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