I think i'm going to change the sending unit next...hopefully it wont cost much.

 

Their should be two sending units on your truck. One for the guage and one for the computer. Make sure you are checking the right one. Also I have heard the putting teflon tape on the treads of the sending unit can make it read wrong. Don't know if this is true or not. Probably only true for a one wire sending unit that uses the block for the ground. The sending unit in your truck is plastic so be carefull removing it. Or you will be digging it out with a pic. My 89 didn't heat the cab that well either. I found the blower switch had shorted out causing the blower not work properly. It would change speeds but would not blow that hard on high. You may want to make sure that the blower is working properly too. Just to let you know none of my gauges work very well in my dash either and I put in after market gauges.

 

Just a thought, but have you checked to make sure you fan clutch isn't engaging at a lower than normal temp? I've been toying around with putting in an electric fan with an adjustable switch to allow my engine to reach a decent temp. Mine also is always between cold and normal and i have replaced the tstat twice with different brand 195 tstats. I have a feeling that these engines (302) run cool easy and I don't think I need my mechanical fan engaging too early in the cooling cycle.

 

Could be that your heater core is somewhat plugged up which would explain the lack of heat. As for what the gauge is reading, we all know how these gauges work. As long as mine show some movement I figure they are working.

Try blowing out the heater core by running water or coolant through it backwards and see if that improves your heat situation.

 

Well, I've driven many Ford trucks by now...my 95 and by buddy's 96 run on the R in Normal most of the time...maybe the O as well. Never have any temp problems with my F-150.

Where is there a 2nd sending unit? I thought there was just one, which was behind the distributor in the top of the intake...It's metal too not plastic. It appears to ahve some kind of thread sealant on it as well.

I just remembered that I have a sending unit from my 302 that I know works and I could put it in if it's the same one...gotta go searchin' for it.