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Thumbnail Filmstrip of 1994-2003 7.3L Powerstroke Max AC Assist Dieselsite MAX Images
WORKS ON ALL 1994 - 2008 F250-F450 Gas Engines as well. In 1994-2008 HD and Superduty trucks, hot engine coolant is flowing through the heater core whenever the heat or Air Conditioning is turned on. The system does not differentiate between the two. This is fine when you are running your heater. However, running the Air Conditioner is a different story. When your AC is on, your cold air is not only flowing across the evaporator coil but it also flows past the heater coil which has hot engine coolant flowing through it. Even with the air flow diverted around the heater core, the heater is still emitting heat just like a radiator. This results in a very inefficient air conditioning system in these vehicles.
This DIESELSITE Air Conditioning Control Valve will automatically shut off coolant flow through the heater core when MAX AC selected. The result is a decrease in duct temperature by 10 degrees or more which will be felt through your vent openings into the cab. This gets COLD!
Install takes about 15 minutes and requires no special tools. Everything you need is included in the kit. Full detailed instructions including color pictures are included.
WORKS ON ALL 1994 - 2008 F250-F450 Gas Engines as well. In 1994-2008 HD and Superduty trucks, hot engine coolant is flowing through the heater core whenever the heat or Air Conditioning is turned on. The system does not differentiate between the two. This is fine when you are running your heater. However, running the Air Conditioner is a different story. When your AC is on, your cold air is not only flowing across the evaporator coil but it also flows past the heater coil which has hot engine coolant flowing through it. Even with the air flow diverted around the heater core, the heater is still emitting heat just like a radiator. This results in a very inefficient air conditioning system in these vehicles.
This DIESELSITE Air Conditioning Control Valve will automatically shut off coolant flow through the heater core when MAX AC selected. The result is a decrease in duct temperature by 10 degrees or more which will be felt through your vent openings into the cab. This gets COLD!
Install takes about 15 minutes and requires no special tools. Everything you need is included in the kit. Full detailed instructions including color pictures are included.[...]
WORKS ON ALL 1994 - 2008 F250-F450 Gas Engines as well. In 1994-2008 HD and Superduty trucks, hot engine coolant is flowing through the heater core whenever the heat or Air Conditioning is turned on. The system does not differentiate between the two. This is fine when you are running your heater. However, running the Air Conditioner is a different story. When your AC is on, your cold air is not only flowing across the evaporator coil but it also flows past the heater coil which has hot engine coolant flowing through it. Even with the air flow diverted around the heater core, the heater is still emitting heat just like a radiator. This results in a very inefficient air conditioning system in these vehicles.
This DIESELSITE Air Conditioning Control Valve will automatically shut off coolant flow through the heater core when MAX AC selected. The result is a decrease in duct temperature by 10 degrees or more which will be felt through your vent openings into the cab. This gets COLD!
Install takes about 15 minutes and requires no special tools. Everything you need is included in the kit. Full detailed instructions including color pictures are included.
Q
Jonathan Franco • 06/26/2026, 10:59:49 PM
The arrow stamp on the valve is it supposed to be aiming towards the wall or towards the pump?
A
06/29/2026, 1:18:31 PM
Instructions come with the product for installation.
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5/5 Stars out of 4 Reviews
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CHRIS DEAN (SCOTTSBORO AL) | August 26th, 2025
EASY TO INSTALL AND NOTICEABLY COOLER AC NICE PRODUCT
Nick (Missouri) | June 29th, 2025
Worth every penny. True 15 minute install that pays itself off the second you crank that AC on a hot day
Paul Becker (Odenville, AL) | January 10th, 2024
Best bang for the buck upgrade there is! I ordered 1 to try out...then ordered 2 more for the rest of the trucks at my shop. In the 20 years I've owned my powerstroke I have never had to turn down the A/C...this past July on a trip from Alabama to Michigan I found myself turning down the A/C periodically because it was too cold in the truck! Highly recommended!
Deron Kauble (Florida) | April 26th, 2021
Simple install took me all of 10 minutes. This made a huge change in the air coming out of the vents. I have a E99 F350, I have replaced the condenser, compressor, fan motor, all lines. I cleaned the evaporator coils and it blew cold but being in Florida I wanted it as cool as possible. I installed this in 10 minutes and it dropped the temp coming out of my vents by 13 degrees. It also eliminated the warm air "pocket" on the passenger floorboard side. My only regret is that I did not find this product sooner!!!! Thanks guys!!!!
Proposition 65 Warning Information -
P65Warnings.ca.gov
Fits: 7.3 Powerstroke 1994-1999
Fits: Powerstroke 1994-2010 (E4OD, 4R100, 5R110) (Automatic Only)
California Restricted
Fits: Universal - 4 Inch Intake Systems