Computer and temperature guage disagree, poor heat, stuck on defrost

[Meat_PoPsiclez]

So for a while (since the end of summer) my air controls always turn on the defrost (ac cycles on and off periodically) no matter what setting except off. I was pretty unconcerned going into winter so I ignored it, but perhaps it's a sign of a bigger problem?

Haven't had the Ex out for a good drive in a while, so I'm not sure when it started, but my temperature guage indicates the engine is always cold, but the computer (obd tool) disagrees. Out for an hour drive, a little offroad, a lot of 60-70km/h roads) and the guage never got past a quarter. Computer is reporting 75-80c, (75 with the heat and fan cranked, climbs to 77-80c when off).

Doesn't seem too hot, hood isnt particularly warm after the drive.

It's only -6c out.
Thermostat failed was replaced in the spring, well tested and it would open perfectly at 180f according to obd when it was hot out (light or heavy load temps held at 180)

Other thoughts, my battery meter reads perpetually low as well.. Maybe I'm just seeing an electrical issue?

 

[lobo411]

Replace the temperature sending unit, which is the temperature sensor for the dash gauge. That's the one that has only one wire connection.

 

[SoHK_alumni]

And, check the vacuum lines and reservoir. Without vauum, the hvac system will default to the defrost vents.

 

[intelisevil]

And, check the vacuum lines and reservoir. Without vauum, the hvac system will default to the defrost vents.

X2 for only having defrost.

You should have a 192º (89c) thermostat, 180º (82) is too cold for the fuel system to work properly.

 

[Turdle]

So for a while (since the end of summer) my air controls always turn on the defrost (ac cycles on and off periodically) no matter what setting except off. I was pretty unconcerned going into winter so I ignored it, but perhaps it's a sign of a bigger problem?

Haven't had the Ex out for a good drive in a while, so I'm not sure when it started, but my temperature guage indicates the engine is always cold, but the computer (obd tool) disagrees. Out for an hour drive, a little offroad, a lot of 60-70km/h roads) and the guage never got past a quarter. Computer is reporting 75-80c, (75 with the heat and fan cranked, climbs to 77-80c when off).

Doesn't seem too hot, hood isnt particularly warm after the drive.

It's only -6c out.
Thermostat failed was replaced in the spring, well tested and it would open perfectly at 180f according to obd when it was hot out (light or heavy load temps held at 180)

Other thoughts, my battery meter reads perpetually low as well.. Maybe I'm just seeing an electrical issue?

This

www.explorerforum.com/forums/showthread.php?t=192842

Also, for the suspected electrical issues, try cleaning the battery posts. As ridiculous as it sounds any little bit of grease or dirt inside the connections cause flaky issues on our trucks. Do not grease the post connections until after they are cleaned and tightened back down, if at all. I prefer dry myself.

edit
the low temp reading sounds just like when the fail-safe thermostat failed open shortly after I installed it. I blame it on the heat soak an engine goes through when it is shut off after a hard drive. It's not uncommon for coolant temps to spike way high while the engine is turned off with no coolant circulating. IMO this natural occurrence can cause a fail-safe thermostat to go wide open where it will "catch" and remain open. Your coolant temp should reach 190 degrees F at least, no matter the outside temperature if the thermostat is doing what it was designed to do. I since purchased a thermostat from the FORD dealer, my scan gauge reads temps at 191F after the initial warm up spike. No matter the outside temp. The gauge in the cluster reads dead on in the center now.

 

[Meat_PoPsiclez]

Thanks for all the tips!
I'll definitely check vacuum, I notice some (very minor) surging using the cruise control, so that likely indicates a vacuum issue too. I never use cruise (until this last weekend) so I hadn't noticed it until just now.

It in fact is a 190 deg thermostat.. Doing the c to f conversion in my head screwed me up (obd software torque gives me celsius) I guess. It definitely ran 190f (not 180 as previously stated) when it was freshly installed. Guess that's what I get for buying cheap parts. I had a hell of a lot of trouble getting the housing not to leak after the first replacement, I can only imagine it's going to be even more trouble this time.

Looks like I probably have three issues at this point, vacuum, thermostat, and electrical. I should really throw a new mass air flow sensor in too. It never ends does it?

I should start with a bath and an engine wash, because I can say without a doubt the engine compartment is dirtier than the outside

 

[1997XLTRollover]

I'm running a stant superstat and I run 190-191 degrees and it rarely deviates more than a couple degrees. Even the warmup "spike" doesn't go beyond low to mid 190's. The only time I see over 200 degrees is under full load running up hill for more than 5 seconds and even then I don't see anything higher than 201-203. I've held it wide open for 15+ seconds and it spikes to 203 and then while still wide open the temp starts coming down to 199 197 ish.

Far as the leak I had that problem too. Odds are the metal is a bit pitted from years of service. Mine was. If that's the case it'll never stop leaking if you just use a gasket. I got a new gasket and put RTV on both sides and haven't had a leak since.