Hi everyone,

I have a 1992 EB Bronco with 351 injection mass air flow. I bought it 4 months ago. I have ran chevys for the past 12 years. prior to that I ran only fords. I switched to Chevys due to my friend selling them. I can say I am very happy to own a Ford again!! I live in Iowa and work in MN. This morning it wa -10 and the a 25 MPH wind giving wind chill factor 0f -35. My defrost is actually doing the job but the air is cool to luke warm with the temp selector maxed out on hot. Also when I switch the **** to blow heat on the floor it is the same way. However if I turn it to Max A/C with it set at the hottest temp and hold my hand at the vents you almost have to move your hand after 45- 60 sec. In this mode it heat the bronco very well. In any other mode at the ouside temps listed above it feel cool in the bronc. Also the radiator was totaly unblocked. I have a 205 degree t-stat in it. It had a 160 when I got it , I took that out right away. I am able to heat well, but why is there such a air out temp difference? If anyone has any ideas please let me know. This is a very ood site with a lot of knowllageable people.

thanks,
Sam

 

Just a thought but have you checked the heater core? Could be clogged. A place to start.

 

Thanks Billybob 69 for your reply. I don't think its the heater core since the air will get very hot in the A/C max mode. it must have something to do with the blend air position. Also in the A/C max mode if I turn the temp **** to cold the air will get very cold so it works right in that mode. What do you think? All the other guys on here must be working long hard hours, I would have expected more responses to this problem. I would think someone else would have had this problem since Broncos are nortorius for have heater problems. Any help would be greatly apprciated.

Thanks Guys

Sam

 

Bronco Sam - I've had a mysterious heater problem for a while now in my Bronco, but I don't think it's the same as yours. Mine blows cold on ac, then if you switch to heat it blows cold. Replaced the heater core, still blows cold. Heater hoses are HOT, so I've about decided it a vacum problem, I don't think the vacum controlled valve under the hood beside the blower motor is working... anyone have tips on fixing it?

 

I am having the exact same problem!!!! and I will be damned if I can figure it out. I am replacing the blower motor and resistor tonight as those are both shot (blower motor sounds like it is going to come out the front for the first five minutes it is on...high only as the resistor is bad as well)

I get cold to slightly less than cold air from all the vents, defrost, and floor but if I change to max a/c it comes out nice and hot..makes no sense.

also what does the vacuum valve on the top to the left of the blower do? I could not find it in the haynes manual (no surprise there!)

forgive me as this is my first ford!

Thanks!

 

I am not sure why you are not getting heat in all of the other modes. But I think that one of the reasons you are getting heat in the MAX A/C mode is that that mode will shut off outside air. It does this to more efficiently cool off your truck. I know this didn't solve your problem, but I hope that it helped.

 

I bet i know the problem here...my 87 bronco did the same thing, what you have to do is open the glove box and pop it down so that you can see behund it. you will see a black cable running in front of the heater core box, it should have a little clip that holds it to the heater core box.Move your heater control switch you should be able to feel it move, if you want a temporary fix slide the heat control switch to hot and you should be able to hold the cable and force it to switch to hot. if not follow the cable towards the passengers side up into the firewall, you will se where the cable controls the out side air push it towards the firewall. this should help,I did this to mine and it did, during the summer for air i switch it back the other way, hope it works

 

The following is good for early to mid eighties, don`t know about the 92 model. You have 3 different flapper doors in you system that direct where the air flows and whether or not you get hot or cold air. More than likely, you have something stuck between one or more of the doors and/or the junk flapper door hinges are broke. You can manipulate them by hand and then plug the vacuum source to get through the winter. Then plan on tearing your dash apart to fix. By the way, some doors are cable actuated and some of them are vacuum operated. Sometimes the cables even break. You can trace them out really easily to see which are which. It is self explanatory once you see the back of your controller and move your levers around. Hope this helps.

 

on your 92 model it sounds as if your having a vacuum source problem that is not allowing your flappers to work correctly. I tracked mine down to the vacuum line that runs out into the engine compartment and works the vacuum pot located on top of your ac condensor box in the engine compartment on the passenger side.

on my 1995 model there was a tiny white vacuum line that run over to this vacuum pot, its made of plastic and deteriorates inside the engine compartment over time. I didnt realize this was the problem and suffered many cold months during the winter without heat. mine started out leaking where the line makes a hard 90 degree turn, and got worse as the hole in the line got bigger and bigger, and ended up not working at all.

I wouldnt have found it if the line hadnt eventually broke one day.

I ended up going to the local auto parts store and found a small piece of vacuum line that woul just barely fit over the end of the broken piece and then run that over to the vacuum pot.

good luck!