high output heater
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Junior User
Joined: Jan 2005
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high output heater
will a high output heater fit in place of standard heater/ac and is it an air conditioner also?? my factory manual for my 74 does not mention a high output heater. was this an option on later 70's?
Post Fiend
Joined: Jul 2003
Posts: 11,945
Likes: 3
From: Spokane, WA
The high output core will not fit in a standard heater box without modifications. A NON A/C heater box with a high output core will bolt right in place of a regular heater. I know high output heaters were used in all the Supercabs and Crewcabs. I do not think (might be wrong here) you can use a heater core from a truck with AC in a non-A/C heater box. The easiest thing to do is keep an eye out for a Supercab without AC that is being parted out and just swap in the heater box.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
there is 3 different heater cores for these trucks one for a/c, one for hi output and one for standard. then the factory deluxe heater used the a/c heater core. it was just an a/c heater box with the evaporator removed.
Elder User
Joined: Jul 2005
Posts: 969
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From: North Texas
I just want to ensure you have checked the basics. They can make a world of difference, and there's no sence spending money if you don't have to.
What temperature is your thermostat? Have you tested it to see if it really works? You could be running cold with a bad thermostat.
Does you radiator have calcium or corosion inside? If so I'll bet you heater core looks the same. You won't get much heat out of it.
Does you cooling system pressurize? Your coolant won't hit full temperature if not.
Do you have a thermal clutch fan? Does it work? Do you have a plain fan? You could be cooling a cold engine.
Have you checked your heater's vacuum hoses, air ducts, and control cables?
What temperature is your thermostat? Have you tested it to see if it really works? You could be running cold with a bad thermostat.
Does you radiator have calcium or corosion inside? If so I'll bet you heater core looks the same. You won't get much heat out of it.
Does you cooling system pressurize? Your coolant won't hit full temperature if not.
Do you have a thermal clutch fan? Does it work? Do you have a plain fan? You could be cooling a cold engine.
Have you checked your heater's vacuum hoses, air ducts, and control cables?
Posting Guru
Joined: Sep 2003
Posts: 1,192
Likes: 1
From: lino lakes, mn
sounds like nyour truck has AC if it does it does the stock heater core is about the same size as the hi output core if you'er asking can I remove the AC heater box and put in a hi output box yes and no you can if you want to rebuild the firewall because the hole for the AC setup is about a foot square and the one for a standard heater is about 5 inches in diameter if you allready have AC and all you want is more heat it's about a wash to go to the hi output heater if you want more room under the hood well then get out the sheet metal tools
Elder User
Joined: Jul 2005
Posts: 969
Likes: 1
From: North Texas
Originally Posted by plowpusher
sounds like nyour truck has AC if it does it does the stock heater core is about the same size as the hi output core if you'er asking can I remove the AC heater box and put in a hi output box yes and no you can if you want to rebuild the firewall because the hole for the AC setup is about a foot square and the one for a standard heater is about 5 inches in diameter if you allready have AC and all you want is more heat it's about a wash to go to the hi output heater if you want more room under the hood well then get out the sheet metal tools
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
also if your truck has a/c , you have a heater valve installed on the heatr hose. it may be closed pull the vacuum line to it and see what happens.
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Cargo Master
Joined: Dec 2003
Posts: 2,735
Likes: 38
From: Sunny Florida
I pulled a high output heater box set up from a 78 4x4 regular cab truck last year at the junk yard. The truck still had the dash trim piece with the high output stick on piece. I have also been told that the blower motors for the high output and AC trucks is one in the same.
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Postmaster
Joined: Apr 2000
Posts: 2,838
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From: SD
Is there a problem with your heater? Are you cold?
I've been told that high output heater was optional on all non a/c trucks. It was STANDARD on all supercabs, crew cabs and Broncos. Also all factory a/c trucks have a high output heater.
So does your pickup have factory a/c? If so, you have a high output heater. But if it's not heating very well, you need to follow derherr65's steps to find the problem. I've also found that bad window and doors seals as well as rusted floorboards make it very hard to stay warm...
Marty
I've been told that high output heater was optional on all non a/c trucks. It was STANDARD on all supercabs, crew cabs and Broncos. Also all factory a/c trucks have a high output heater.
So does your pickup have factory a/c? If so, you have a high output heater. But if it's not heating very well, you need to follow derherr65's steps to find the problem. I've also found that bad window and doors seals as well as rusted floorboards make it very hard to stay warm...
Marty
Last edited by 73Custom; Dec 12, 2005 at 08:24 AM.
Post Fiend
Joined: Jul 2003
Posts: 11,945
Likes: 3
From: Spokane, WA
Originally Posted by 73Custom
I've been told that high output heater was optional on all non a/c trucks. It was STANDARD on all supercabs, crew cabs and Broncos. Also all factory a/c trucks have a high output heater.
The blower motors in non-AC trucks with HO heaters are the same for non-AC trucks with regular heaters. They are not interchangable with the AC blower motors. The only difference between the HO heater boxes and the standard units is the size of the heater core. IIRC the heater cores for the HO units are about 2" longer. The HO core would fit into a regular heater box EXCEPT that there is a plastic wall in the way which holds the bottom of the regular core. If someone had some patience they could probably cut this wall out and move it down or build a new one to accomodate the HO core. If you pull the core out on a regular box you'll see what I'm talking about. To my knowlege there is no marking on the outside of the heater boxes indicating if it's standard or HO. The only way I've ever been able to check this is to pull the core.
Mountain Pass
Joined: Apr 2004
Posts: 132
Likes: 1
From: Montana
I have to agree with Ivan. I replaced a heater core (HO) in my standard, custom, strip down f250. The only difference was the size of the heater core. My other truck has a regular heater core (again replaced) and it was smaller. Neither truck has air and the motor seems to be the same.
Senior User
Joined: Jan 2005
Posts: 189
Likes: 0
From: Elkins, WV
Just great.. Thanks Ivan.. I checked my truck (non A/c model from Texas) and sure enough it is only a STANDARD HEATER CORE...
Now I have HO heater core envy and I am going to need to upgrade with the big boys. I have recently moved to Kentucky and we got a slight drizzle of snow today.. So looks I have an excuse to go down to the auto parts store this week to buy a HO heater core. 
I think my truck still has the original 28 yr old heater core in it.. no wonder it doesn't work too well..They sell the HO core for about $35 at Advance Auto parts. Photo below..
Now I have HO heater core envy and I am going to need to upgrade with the big boys. I have recently moved to Kentucky and we got a slight drizzle of snow today.. So looks I have an excuse to go down to the auto parts store this week to buy a HO heater core. I think my truck still has the original 28 yr old heater core in it.. no wonder it doesn't work too well..They sell the HO core for about $35 at Advance Auto parts. Photo below..
Senior User
Joined: Jan 2005
Posts: 189
Likes: 0
From: Elkins, WV
Originally Posted by RTM
I pulled a high output heater box set up from a 78 4x4 regular cab truck last year at the junk yard. The truck still had the dash trim piece with the high output stick on piece. I have also been told that the blower motors for the high output and AC trucks is one in the same.
Thanks.