No heat in my van...why?

[Reeves]

I hope I'm posting this in the right section...forgive me if I'm not.

Since I've owned my van (about 6 mos.) it's had an odd heating problem. The temperature gauge would always go to HOT evertime you first left in the morning, or coming home from work (after sitting a while) and stay there for a short period (maybe a minute) then go to COLD, then go to normal. I figured it was either a T-stat problem, or a blown headgasket. It didn't bother me too much, since I planned on replacing the head and t-stat anyway.

Well, it now has head, headgasket, t-stat, and temp sensors all swapped out, and it is still acting very strange. The temp is all over the place as soon as you take off, it will eventually settle out just below midway of the gauge.

But, I now have NO HEAT!!

I removed the lines right at the heater core and flushed just the heater core with full garden hose pressure...seemed to be just fine. I just got back from a drive though, and the lines going to/from the heater core are barely warm, but the radiator hoses are hot. The gauge is still all over the place.

Any ideas?

Thanks!

[Tony Hanna]

I've seen the heater bypass valve die and cause the heater not to work. You can test for this by routing the hoses around the bypass valve.
Another big possibility is trapped air. It always took me an hour or better of bleeding the air out of the cooling system in the Daytona before the gauge would act normal and the heater would work.
HTH,

[JohnnyLightning86]

I would to see if the heater line is clogged coming out of the water box on the head The Heater core may also be clogged. And don't assume a new t-stat is working properly.

I suggest you get one of those cooling system flush kits and back flush the system. Be sure to run from flush in it for a good while before back flushing. I usually like to get a long hose I can connect to the heater core and flush that one component thoroughly by itself. If the heater core is clogged, or the heater bypass is bad or the valve is not working properly, and/or the t-stat is bad, I could see possibly having some odd heat problems since the only time the water box (location of the t-stat and temp sensor) would cool down is when the t-stat opened.

That t-stat you got wouldn't happen to be a Stant brand would it? I have known several people including myself have problems because of them. Even to the point of causing a blown head gasket.

[R/T]

Does the heater control valve have the tiny vac line connected to it??

The control valves are a known source of problems....

[Reeves]

The heater control valve is only used when the A/C is on. I did check it's operation and it is functional.

I flushed the heater core itself with a garden hose and it seems OK.

I am hoping there is just air in the system, as it looks like on a van that the heater core is the highest part of the system?

I will also try changing the t-stat. Maybe I can find a hotter one.

[Subliminal]

Yeah, i'd first check for air in the system. With the nose facing uphill, or the front end on ramps, pop open the radiator cap (carefully if it's hot). Let it run until the thing warms up fully, and the t stat opens up, and see if the level goes down any. Fill as needed.

Another thing that often helps with this is when you refill the system, keep that nose up hill and while cold, crack the two bolts holding the stat on. Fill the radiator up until it spooges out the t stat, tighten those bolts on the t stat, then fill it till its up to the neck of the radiator, and you're done.

When my van had no heat last winter, it turned out that the little arm that controls the heat bypass had slipped off. It's on the two heater hoses going to the core.

[Clay]

Also you can use the plug above the thermostat to bleed air...... thats what its for I believe.

Plus, when installing a new thermostat, drill a 1/16" or 1/8" hole in the outside part of the flange, and put that at the top of the stat when you install it. This helps get the air out of the system as well.

[Subliminal]

Also you can use the plug above the thermostat to bleed air...... thats what its for I believe.

6 TDs so far, with mulitple heads on a few of them, and I have yet to get one of those plugs out.

Everytime I get a new TD, though, I get excited about the prospect of that plug coming out...but it never happens.

[Clay]

6 TDs so far, with mulitple heads on a few of them, and I have yet to get one of those plugs out.

Everytime I get a new TD, though, I get excited about the prospect of that plug coming out...but it never happens.

hehehehe

[scotty] She needs more heat captin!!!!!!!!!! [/scotty]

[turbovanman²]

Your going to hate my answer but your heater core is plugged. Thats the reason why your heater hoses are lukewarm, as theres no flow going thru the core. The garden hose doesn't have enough volume to show up.

I do this on mine everyyear and it works, but one day, I am going to replace it and when I do, you will hear me scream for days-its not a pretty job.

Remove your heater hoses, blow out the left over water inside the core, add a couple feet of new hose and tie them so there pointing up. Fill the core with CLR, let it sit for an hour or 2. Carefully aim the hoses down and away from anything paint or such you don't want damaged. Run your garden hose backwards, thru the passenger side nipple. I get those flush tees with the hose adaptor, then block off one side and hook up my hose gun, then blast it backwards or a rad shop can do it, they have air added to there water supply so they can really knock it and blew that crap out. Works for me every year. NOW, be warned, this could cause it too leak so be prepared to do the heater core. It hasn't happened to me yet but it could.

Thats also why the temp guage jumps around, the inconsistent flow thru the core screws up the cooling system. My guage used to dance when the core got plugged up. I have since done the #4 coolant mod and that almost stopped, even with the plugged core.

[Clay]

I dont know that I necessarily agree Simon.

If the heater core were plugged you would have one hose hot, and one hose cold.

Both hoses cold indicates no flow through either hose.

clay

[turbovanman²]

I dont know that I necessarily agree Simon.

If the heater core were plugged you would have one hose hot, and one hose cold.

Both hoses cold indicates no flow through either hose.

clay

Thats why were on a forum, open to all inputs but I go thru what he goes thru every year,

[Clay]

Thats why were on a forum, open to all inputs but I go thru what he goes thru every year,

So yours does the same thing? (no heat in the lines, plugged core) Im just going by experience with other vehicles, but you know these TDs a lot better than I do!!

clay

[turbovanman²]

So yours does the same thing? (no heat in the lines, plugged core) Im just going by experience with other vehicles, but you know these TDs a lot better than I do!!

clay

Yep, every winter I have to flush the core. To replace it, you need to remove the dash etc, 6-8 hour job and I don't want to do it UNLESS I have to, lol!

[Turbodave]

I've had to flush the core on both of my vans also. My old man has got a garden hose to heater line adapter he made with a schrader valve on it so you can give it a shot of air, works great for breaking the crud loose. It's suprising how much can get built up in there.

Our engines have consant flow of coolant through the heater core, even before the thermostat opens. If there isn't flow through the heater lines the coolant in the engine doesn't flow and you get peaky engine temps until the thermostat opens. When the bypass valve is switched open the heater core is bypassed, but coolant is still allowed to flow.

So, one way to check if the heater core is the problem would be to run the van with the A/C on and in the Max setting which should bypass the heater core (or just hold the bypass valve open manually). If the temps respond better and the heater hoses get hot that should point at a restricted heater core.

[Reeves]

For anyone who has had the HVAC system out of a van, does it have a flapper door to block off the heater core at anytime (like for A/C or cool vent?)

Maybe this could be blocking my heat?

[turbovanman²]

For anyone who has had the HVAC system out of a van, does it have a flapper door to block off the heater core at anytime (like for A/C or cool vent?)

Maybe this could be blocking my heat?

Yes, thats how they redirect the heat. I haven't had a good look at mine but based on the fact I have seen lots of heater boxes, trace the heat control cable to the box, if you can see it moving and can hear a thud, chances are, your core is bad.

[Omnious]

In my van, The flapper door was the problem. iIcould push the cable all the over to the warm, and still have semi cold air. I removed my radio and shoved my hand in there to help push the lever to where i wanted it, now it's warm. I would suggest trying this, Good Luck

[Stevien1]

Yep, every winter I have to flush the core. To replace it, you need to remove the dash etc, 6-8 hour job and I don't want to do it UNLESS I have to, lol!

C'mon, the 1st gen minivans have to be one of the easiest heater cores out there (well, Chrysler at least). I did the one in my van a few months ago in one and a half hours. It doesn't have a/c, so add in another 15 minutes to evac/recharge. 6-8 hrs to do a heater core or even an evap? Maybe on a Jeep Liberty or late model Chrysler minivan.

I'll make you a deal Simon- I'll put a heater core in your van if you align my van!

-Chuck James

[Subliminal]

Simon smokes a lot of pot. His version of reality is slightly askew from the rest of us.