Delayed cab heat
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Senior User
Joined: Jul 2006
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From: Sandy Lake, MB
Delayed cab heat
1991 f-250 xlt lariat. I have had this truck for a year now i the other day i relized that i takes a long time to warm up in the cab even when the truck is at full operating temperature. The only time it gets really warm in the cab is when i bring her up to operating temperature and let it sit at idle for 15 minutes or so. Otherwise it never gets warm to the point where i have turn the heat off full blast. The truck itself warms up fine and sits where it is supposed to be.
I can control the teperature setting for hot and cold but to switch it from defrost to floor or vent settings is pointless. No matter on what setting, air is coming out all vents. The temperature is getting colder and colder and i hate driving while freezing. Is there a filter? maybe a blockage? Any ideas?
Even when pulling a trailer the cab does not warm up very well until i let it sit at idle for a while. My dads truck heats up within 10minutes after starting the truck in the morning and gets so hot that you have to shut the heat off.
Thanks
I can control the teperature setting for hot and cold but to switch it from defrost to floor or vent settings is pointless. No matter on what setting, air is coming out all vents. The temperature is getting colder and colder and i hate driving while freezing. Is there a filter? maybe a blockage? Any ideas?
Even when pulling a trailer the cab does not warm up very well until i let it sit at idle for a while. My dads truck heats up within 10minutes after starting the truck in the morning and gets so hot that you have to shut the heat off.
Thanks
Elder User
Joined: Sep 2005
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From: Delta B.C.
How old is the Tstat? if it is stuvk open at all it can take forever to get warm..
If you let it warm up, open the hood and put your hand around the hoses going to the heater core are both hot???
Does the hose from the water pump go to the heater core neck closest to the fender??
If you let it warm up, open the hood and put your hand around the hoses going to the heater core are both hot???
Does the hose from the water pump go to the heater core neck closest to the fender??
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
Since the cab heats up sitting still, I would suspect the adjustment on the air blend door.
If your truck was built after April 1991...... there is a cable adjustment in behind the glove box. You must gently but firmly, pull the white lever to allow the red barrel to move..... in the correct direction to seat the door more firmly.
Side effect could be in winter nice warm cab, in summer lowered cooling effect with A/C on....... you may have to adjust the cable summer and winter. Many have put a shut off/redirector of the coolant to the heater for the summer.
Bulletin # 91-19-9
Dated Sept 18, 1991
If your truck was built after April 1991...... there is a cable adjustment in behind the glove box. You must gently but firmly, pull the white lever to allow the red barrel to move..... in the correct direction to seat the door more firmly.
Side effect could be in winter nice warm cab, in summer lowered cooling effect with A/C on....... you may have to adjust the cable summer and winter. Many have put a shut off/redirector of the coolant to the heater for the summer.
Bulletin # 91-19-9
Dated Sept 18, 1991
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Senior User
Joined: Jul 2006
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From: Sandy Lake, MB
Im not sure when the tstat was changed last but that would explain in temperature fluxuations once in a while. As far as i know both heater hoses get warm at operating temperature. I have checked all of my vacuum lines and they all seem to be ok but my vacuum pump is only putting out about 17 psi. I am going to take a look at this adjustment behind the glove box. Is there anything that has to be removed? My A/C is not working because of a bad leak somewhere in the system so thats not a problem.
Thanks for all the replies.
Thanks for all the replies.
Lead Driver
Joined: Jan 2005
Posts: 7,782
Likes: 221
From: Huntington Indiana
The heater hoses should be just as hot as the radiator top hose if you are getting full flow thru heater core. Wonder when last system flush?
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Senior User
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From: Sandy Lake, MB
Im not sure on the maintenance history. The guy i bought it from tryed to fix things and he is not mechanically inclined at all. I bought it not running and did alot of the fuel system. New battery cables and gear reduction starter and it started.
During the summer i blew a heater hose and lost the majority of my antifreeze. Luckily i caught it before i overheated it. I had spare heater hose but no antifreeze so i ran straight water in it for the day. I ran fresh water through everything including the heater hoses and it came out the other side clean and fairly easily. There is 5 month old antifreeze in it right now.
Tomorrow morning i will check everything out and get back to you guys.
Thanks
During the summer i blew a heater hose and lost the majority of my antifreeze. Luckily i caught it before i overheated it. I had spare heater hose but no antifreeze so i ran straight water in it for the day. I ran fresh water through everything including the heater hoses and it came out the other side clean and fairly easily. There is 5 month old antifreeze in it right now.
Tomorrow morning i will check everything out and get back to you guys.
Thanks
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Senior User
Joined: Jul 2006
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From: Sandy Lake, MB
Well i checked my heater hoses and they were hot after going down the highway. I still havent had a chance to take a look behind the glove box. Today everything seemed to be heating alright but it was +2 and sunny all day so that probably helped. I am not exactly sure how to get to my heater core to check everything out. Any one know how?
Elder User
Joined: Sep 2006
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To get at the heater core is no easy feat, but if is'nt leaking, there's point at looking at it...if both heater core hoses are equaly hot to the touch, I don't think you have a problem with the core. Air block was just a thought, it happens, but not very often...
-have you checked the vent door as PCL7.3 suggested
-does the defrost setting work better than the heat setting
-is your rad topped off
-if you use the A/C controls [I know it's not working] you should hear a vents opening and closing powered by the vacum pump....if this is not operational, one or more vents might be open and you are not getting proper air flow??
-have you checked the vent door as PCL7.3 suggested
-does the defrost setting work better than the heat setting
-is your rad topped off
-if you use the A/C controls [I know it's not working] you should hear a vents opening and closing powered by the vacum pump....if this is not operational, one or more vents might be open and you are not getting proper air flow??
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From: Sandy Lake, MB
I havent checked that vent door yet but i will do that tonight. The defrost setting makes no difference in heat change. The rad is topped off with antifreeze and is at -35. As for changing the A/C controls, i have not tryed that so ill check that tonight as well. If one or more vents are open, how do i change that?
Elder User
Joined: Sep 2006
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Well if it is a stuck a/c vent it could be little more difficult to fix....I'm not familar with a 91 dash, so I'd be guessing.
When you try your a/c tonight, try it with all 3 fan speeds, you should have good output at high speed, when changing the settings [air direction] it should have the same output....is air output the same as when you have it on defrost and or heat?
When you try your a/c tonight, try it with all 3 fan speeds, you should have good output at high speed, when changing the settings [air direction] it should have the same output....is air output the same as when you have it on defrost and or heat?
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Senior User
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From: Sandy Lake, MB
Ok i went and checked everything and this is what i came up with. PCL7.3's flap was nice and snug and moved when i adjusted the temperature. bc6.9, i tryed what you said and no matter what setting nothing moved, nothing made noise. I found the actuator controlled by vacuum and no matter what setting whether it is vent, A/C, defrost or anything there is no change in the actuators position. I can move it. There is very little vacuum if any at all when i change the setting. With the fan on sull power and me changing the position of the actuator, i can change the air in the direction that i want it to go. When i was playing the this actuator i found that i was getting alot of heat so as strange as it is, that problem is solved. Now to figure out why there is no vacuum.
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From: Powell River B.C.
The selector switch itself is both electric and vacuum. All the plastic hoses to the switch are incorperated into one connector block like an electric connetor. Check it for loose, or the single hard plastic line that runs the system from the manifold may have a crack in it someplace, also reducing your overall vacuum pressure.