Blower works fine. A/C works fine. Anti-freeze not fouled. New thermostat installed. Blend mix door behind heater coil opens and closes. Supply and return lines to coil are different temps. Only gets slightly warm. Coil hot to touch on left side when looking at it. Anyone have knowledge where to look next?
Thanks for any and all help.

 

Sounds like a stuck new t'stat or significant restriction in one of the heater core lines.

Your posted observations strongly point to the stuck t'stat though.

 

Based on what you wrote, I'd say there are a few possibilities.

One is that your coolant system isn't full yet from replacing the thermostat. It takes a few cycles of running the system with the coolant cap off and topping off with coolant to get all the air out of the system.

Another possibility is a bad thermostat--happens more often than one might think. It's best to test them before installation by placing them in a pan of water on the stove, with a thermometer, and making sure they open at the correct temperature.

Third, you may have a blocked heater core. Back-flushing it sometimes works.

Jason

 

The new thermo was tested before install to demonstrate to my apprentice how the thermo opens.
Should the coil be replaced or serviced? The anti freeze is not fouled in that it is clear besides the obvious green tone.


Thanks for Your Help and advice.

 

thanks for your answer. the vehicle has been driven appx. 60 miles w/o change to the coolant level. I'm leaning towards the block core but confused how would clog and anti-freeze is clean. Normal occurrence?

 

There is a restriction in the hose feeding the heater core, where it exits the top of the engine block. Its less than 1/4" in diameter so its entirely possible that has caught something circulating in the water jacket and impeding flow through the core.

You can feel for that restrictor by squeezing that hose beginning near its end closest to the block them working along until you find it. Its solid and can't be missed.

Once engine is up to operating temp feel for a temp difference on both sides of the restriction. (An IR thermometer would be great for this if you have one.)

If the temps across the restriction are close to operating temp then its entirely possible the heater core itself is clogged---not unheard of even if a bit rare on your year/mileage vehicle.

If its the heater core we should be able to talk you through that too---been there, done that and its not impossible.

 

Great. Will check that out. Its raining here in Jersey. I will check that out. Thank You

 

no restrictions in coil or flow restrictor on supply @ front of engine to coil. blew air thru reverse flow and a little muck came out. reassembled and drove. air is warmer but seems the vent is not having as strong air flow. When switching between floor and vent (or a/c) air very briefly flows stronger then dies down. Fan speeds work (sound) as expected at the different levels.

 

I can't remember but isn't there a heater control valve located on one the the hoses going to or from the heater core? I've heard of a few guys that have had to change that valve because of no or low heat. Just a thought.

 

Have you owned the van since new? the reason i ask is that the muck you mention could be the PO who put a can of stop leak ( stop heat ) into the coolant at some point and the heater core could be plugged.

wouldnt be the first time i saw this , good luck its gettin cold

 

Blowing air threw the heater core is not the correct way to clean it out.
Garden hose with 35-40 psi works much better, and if the air pressure is too high, it can cause damage to the core.

Mike1 is correct that the '03 has a heater control valve, which does not let coolant flow threw the core in the summer month, and the heater core plugs up with stalemate water for months, causing it to "plug"

Also, it might be worth it to pull the fan motor out of the heater box, and check for "garbage" inside the box, I've cleaned out mouse nests and scraps of paper from heater boxes in the pass.
When you write that it blows strong, and dies down, it's worth checking inside.

 

No, there are not any valves factory-installed anywhere in the '03's----I have one of these one so know of what I speak. In fact the heater control valve scheme hasn't been used at least from '92 forward.

Cagey1 your air flow through the vents and how it seems to divert itself is caused by an issue with the vacuum control system. Typically there is a leak somewhere in the various tubing runs, most often the reservoir and/or associated check valve has failed/is failing. That's another issue not necessarily related to your lack of warm enough coolant flow.

Wildman is correct about flushing your heater coil---his recommendation would also double as an ersatz flow test as well. If gunk like Stop Leak, etc has been added it could very well be plugged up, at least as far as water flow is affected. Air under that much pressure might seem to be flowing freely but that's not the same as coolant flow.

I recall when I replaced those same heater hoses even at 170K miles there was nothing solid or gunk-like anywhere in them. Tough to know how much or what kind of gunk you found but that's certainly worth looking into---from where did it come etc?

Also a good idea to check the blower motor cage and heater box as suggested. While any issues there would certainly reduce air flow it shouldn't affect the too low coolant temps you're experiencing.

Next up is the water pump itself---those have been known to pump less coolant which could be at play here too. I'm not sure exactly how to test this pump for proper flow but I'm assuming the engine temps are okay, within normal range?

I will say we first need to solve the issue why the heater core and its connecting hoses aren't reaching their proper operating temps.

You've never said one way or the other if you're using any sort of thermometer for any of this diagnosis? Even a cheap IR model would be good at this point. The stem type inserted into the coolant reservoir would give an idea how the coolant flow through the block and radiator is doing.

 

Thanks for all Your brain dredging for me.
I have owned the van since new. just about 170k miles.
I will take readings w/ the IR therm.
Is the vacuum schematic the same on the 97 & 03 E250?


Thanks to All

 

Yes.

Geeesh need 10 Characters!