Alright I've been tossing this around for months and now that is 2 degrees outside I really need to get this figured out.

My 2002 150 has a EATC module. My problem is only my defrost and vent options work. While they are the only two options that work my heat barely gets warm. I noticed during summer my AC barely gets cold which isn't a big issue. I need ideas. I've been told its either blend door or the EATC module. Is there an easy way to figure out which one is the issue?

 

Have you searched YouTube on how to check/test them? A lot of helpful videos for troubleshooting issues.

If all you're getting is defrost and dash vent I'm guessing blend door actuator or the actuator resistor. My '97 Explorer did that and it was a bad resistor. The resistor should be on the outside of the heater box under the hood with a 2-3 wire connection and 2 very small screws holding on a small rectangle shaped box. $10.00 and 20 minutes to change.

As for poor heat, how's the coolant? Weak coolant does not create good heat and can actually cause you system to freeze up. Had that happen before too. Best case you blow a radiator or heater hose, worst case crack the block. A coolant tester is a couple bucks at Walmart.

​​​​It's possible that could effect the a/c too but unlikely. That would most likely be a low freon charge though.

 

I have looked up a couple videos but I do get a slight variation in temp like the blend door is turning. Like when I set it to 85 or 90 I do get lukewarm air and when set at 65 or 60 I get chilly air. But its never hot or cold.

The coolant is brand new and reads -50 on a test.

 

Check to see if you are getting hot coolant into and out of the heater core.. get your motor up to operating temp 185-190 and then check the heater hoses running in too and out of the firewall.. theses 2 hoses provide heated coolant to your heater core.. they both should be very warm or hot to the touch when heat in the cab is selected. If just 1 is hot the core is clogged.. if neither is hot.. check you thermostat.. a wore out impeller on your water pump could cause low coolant flow also..if all under the hood is good then you have a blend door problem.

 

The left side hose is pretty much cold still after truck has been running for about 30 minutes. The right side hose is burning up. But the core flushes perfectly fine.

Edit: after shutting the truck off the left hose does get hot

 

Sounds like the heater control valve is stuck closed.

 

Yep ^^^

 

Ok... so I'm not stupid when it comes to vehicles but here is the real stupid question... on a 5.4 f150 where is it? 😂 I've been looking for 30 minutes and can't find this control valve.

 

If you guys are talking about one of these, neither my truck, nor my Expedition have them.

 

Yeah mine doesn't either. They sell replacements for them but they aren't on my truck. I've looked all over and finally found a forum post where a Ford tech said 2002 4.6 and 5.4 don't have them unless a mechanic has added one.