No Heat

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Cruzerman

Cruzerman

Joined
Apr 23, 2005
Threads
75
Messages
3,365
Location
Oregon
I have a '93 FZJ80. The heater has always worked exceptionally well. However, all of the sudden, I get no heat out of the front or rear heater. Car comes up to temp just fine, but no heat.

I have taken the control cable off the heater control valve and manually moved the lever. Still no heat. Does this mean the heater control valve is bad? It looks OK from the outside and it just seems like there is little / nothing that could go bad in a stupid valve. TIA.
 
With theAC on, and manually moving the valve, does the air go from ice cold to at least luke warm?
 
Someone one once posted that by now all those valves leak.
I took his advice and ordered one up, OEM on Ebay.
Removed my old valve and sure enough I could blow air thru it when it was moved to closed.
Maybe they should have made these out of Aluminum or brass as the black plastic is known to fail.
 
With A/C on, it blows ice cold. Temperature does not seem to change (at least noticeably) when I move the valve from one way to the other. It used to have so much heat that when I turned the A/C on and had the heater turned up, it was still way hot.
 
Sounds like the valve is wasted, assuming the coolant system hasn't been worked on recently. Take the heater valve off and inspect the actually valve inside. How many miles on it?
 
225K on vehicle. I was going to take off the valve, but was hoping to have the new valve in hand first. Looks like I need to remove the valve first and then order on if needed. Unless there is some other way to be sure it is the valve?
 
It's winter, so just get a double barbed 5/8" fitting and 2 Qty 1" Hose clamps and leave valve out till new one comes in.
Just an idea.
 
Cruzerman,
At 225000m a new valve would be more PM than not, I 'd suggest just replacing it.
Do as 'Hornd' suggests and use the windows as temp adjusters for a couple of days. Better warm than freezing. LOL
Mac
 
Well, I took off the heater control valve. Nothing wrong with it, so I put it back on. And I was wrong about the rear heat. It works, just no front heat. Blocked heater core? What's next? And while I'm asking questions, how in the hell do you take off those cotter pin clamps?
 
Cruzerman said:
Well, I took off the heater control valve. Nothing wrong with it, so I put it back on. And I was wrong about the rear heat. It works, just no front heat. Blocked heater core? What's next? And while I'm asking questions, how in the hell do you take off those cotter pin clamps?
Click to expand...
i have the EXACT same issue and am having the dash heater core flushed as we speak... hopefully i'll be able to update you tomorrow...


also, my mixer valve busted over the summer and i replaced it at that time... it totally disintegrated and i'm just assuming pieces of the brittle plastic made it right in to the dash heater core...

rear works great, and since it's not particularly cold right now, has been enough for me

i also have an issue where i put the arm on the mixing valve on wrong when i replaced it and now my cable seems to be disconnected under the dash... not sure how to solve that problem, but it doesn't move when i move the temp slider....
 
One way to find out, buy 6' of clear tubing of the proper diameter and a Garden hose thread barbed fitting and a 5 gallon bucket. Remove the heater hose going into the top of the core and put 3' of Clear tube on it and the remove the bottom hose and replace with the other 3' of clear tube put the bucket under the top hose and push the barb end with attached garden hose into the bottom end hose. Then slowly turn the garden hose on and back flush the core. Then swap hoses and send water through the correct way and go back and forth until you get good solid flow and no more rust and sediment. Then put a funnel in the top hose and bucket under the bottom and poor coolant through until it comes out the other end undiluted looking. ReAttach original hoses and bleed the system and see if it helps. If not you may be working with a bad water pump. Just did this procedure to my buddies Heep wrangler. He has never had cab heat, flushed his heater core and found so much metal and rust I decided to look at his water pump. It had no fins on it lol. Yet he never had overheating issues?
 
Coolant level is fine. I will try back-flushing the system this weekend. A side question: I have some unopened antifreeze that is probably 10 years old. Does antifreeze have a shelf life or is it good forever?
 
Anti-freeze is generally good until mixed and used. You can use a hydrometer for antifreeze to see if it's any good if you're concerned.
 
welp, i just got my truck back from having the dash heater core flushed.... still no heat out of the dash, but still do get heat out of the rear...

i'm pretty stumped... only thing i can think of at this point is some of the hoses leading TO the heater core, after the split to the rear being clogged

i sort of wish there was a simple diagram about how the coolant flows in this thing, it's kind of confusing...

starting to wonder if my cable on my mixing valve is moving a air door too, and the fact that it's not working is causing the problem
 
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Discovered this morning that my 93 80 has heat from rear heater but not front. Going through same trouble shooting process...Just put the new radiator in and plenty of fluid. Is air-lock possible in this system?
 
Air can get trapped in the system and cause a no heat issue, but I'd think it's a no heat at all, not just the front. Park on a steep incline, nose up, and allow to run for awhile to get up to normal operating temps without the rad. cap on. Maybe it'll burp some air.
 
OK. So I finally got some time to re-visit my (lack of) heat issue. Since I hadn't done any service to the radiator since I bought it, I figured that even though a plugged heater core was not the problem, the coolant needed changing anyhow. So I back-flushed the heater core, and flushed the heck out of the entire cooling system. It is now full of fresh glycol / water. However, it barely has any heat (with the control valve manually opened).

So, it looks like Phil and Beno are (once again) correct. With the control cable off, moving the temp control does not more the cable. So I'm pulling out the service manual as Phil suggested. Any hints / tricks / known issues? I haven't looked yet, but I assume all the things I need to check are buried in the dash? Not looking forward to this...
 
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