intermittent heating issue...

[dlphnfn]

My 'Sploder is a 2000 EB 4.0 SOHC. Its got the electronic hvac controls. My wife claims the heat works about every other time. I drove it the other day. I set it on 78 and it started COLD even though it was warm and then just started blowing hot air. She says it also blows cold air when it should be blowing hot air. Im only guessing the issue is a clogged heater core. Anyone else agree with me?
Is there a how to on that or just "figure it out stupid"?
Thanks guys.
Erick

 

[Dave 1955]

I think I read where the premium heater can be put in a diagnostics mode?

 

[dlphnfn]

Just found this...
Push off and floor at the same time, release them, then press automatic.
I'll test in the morning. Thanks!

 

[RomeovilleIL]

Tests: open hood with engine warm and heat on high, both heater hoses should be hot and close to same temp. If not, then either plugged core or malfunction heater control valve (vac leak or broken).

If both hot, then check for interior functions. On EATC, run diagnosic. If no errors then drop the glove box, remove blend door control and check for function. Also check for broken blend door from top by inspection with mirror/flashlight and hex key.

There are good right-ups with pics on how to fix all of these issues. Search is your friend.

 

[sloop]

i'd replace the thermostat. mine was stuck open most of the time and the air was never hot from the heater. it was on my to do list for a few years until yesterday.

 

[1992fordgreen]

Thermo could be bad.

 

[dlphnfn]

Thanks for help so far. I've flushed out the heater core. It's clean as can be with great flow. Diagnostic on eatc returns nothing. Just lights up everything.
Both lines going through firewall are very hot when the engine temp is up to normal.
Still need to check the blend door. Hoping that's not it. I had that fixed by a dealership a few years ago...

 

[koda2000]

if both heater hoses are hot at the firewall, then the hot water is flowing to the heater core. it sounds like the blend door is not opening. there is a quick/dirt fix (requires cutting a hole in the heater box). i don't care for this method, but replacing the blend door is a lot of labor. make sure the motor that opens the blend door is working properly first.

 

[dlphnfn]

Thanks Koda...
On the actuator. I just took it out. (SMALL SPACES!!!) I then turned the heat all the way to 90 on VENT. Then waited a couple seconds, then all the way to 65. Shouldn't I see the actuator "actuating"? It does nothing. Weird though because my EATC test came back "888".
Am I right in assuming it's the actuator?

 

[koda2000]

Thanks Koda...
On the actuator. I just took it out. (SMALL SPACES!!!) I then turned the heat all the way to 90 on VENT. Then waited a couple seconds, then all the way to 65. Shouldn't I see the actuator "actuating"? It does nothing. Weird though because my EATC test came back "888".
Am I right in assuming it's the actuator?

the EATC diagnostic really doesn't tell you much (pretty useless really). seems to me another poster recently had a similar problem and it turned out to be the EATC. search back through the past couple of weeks of postings to find his thread.

 

[RomeovilleIL]

If the actuator motor does not turn when you change the temp setting on the EATC, most likely the actuator is bad (like 90%+). Most times the dorman replacement does not respond to the system. You will need to get the motorcraft actuator. Suggest you buy from somewhere that allows returns on the off chance it does not work and the EATC has a fault.

 

[dlphnfn]

I pulled the ATC actuator out and called Ford to see if they had any more. Put it back in and it worked! Still no hot air but I can feel the actuator moving. Then I ran the test and it came back with 025.
My wife went to get donuts this morning and said no heat on the way there but had heat on the way back. More of an issue than the engine being at running temp. Is very sporadic.
I'll look for that other thread too. Thanks.

 

[koda2000]

I pulled the ATC actuator out and called Ford to see if they had any more. Put it back in and it worked! Still no hot air but I can feel the actuator moving. Then I ran the test and it came back with 025.
My wife went to get donuts this morning and said no heat on the way there but had heat on the way back. More of an issue than the engine being at running temp. Is very sporadic.
I'll look for that other thread too. Thanks.

just because the actuator is moving, it doesn't mean the door is moving.

 

[dlphnfn]

The issue seems super weird to me. I just went to a "you pull" junk yard and got an actuator and EATC unit. Swapped both in and exact same issue. Still getting 025 on the EATC diagnostic test too.
Kinda starting to piss me off actually. Every time I stick my hand up in that slot where the actuator goes, there is a little fiberglass lip that injects shards in my knuckles!
I can freely move the door with my finger tip, but I haven't confirmed that the door is actually moving. That would kill me too... I found my old thread when I had that happen last time. Ford replaced it for $700 I think...

 

[Turdle]

Hmm, I wonder if there is an issue with vacuum which is causing the heater hose bypass valve to open and close at random.

 

[dlphnfn]

Good Lord. You guys are going to kill me.... I checked the coolant. Then I add a gallon. Now the heat works perfect. Grrrrr.... I blame it on my contour and sable not having radiator caps. You fill those from the over flow tank. This one doesn't work like that I guess. The over flow tank is spot on and has been. Maybe I should be looking into that.

 

[Turdle]

yeah, the reservoir outlet can become clogged.

 

[RomeovilleIL]

Might want to find out where a gallon of coolant went.

 

[koda2000]

once you fill the rad once, you should only be adding coolant through the reservoir. if the rad doesn't suck it in from there you may have a cracked or clogged hose or even a bad radiator cap.

 

[dlphnfn]

Yep. That's my next task is figuring out where it going and why it's not refilling.