Heater core bypass, stupid?

[95burban]

Love the OBS fords, I had a white 97 crew cab short bed 4wd 7.3 with red interior. Great trucks!

 

[rob249]

Fantastic ac too, best I've ever had. I was getting 38f air at the vent in 110f heat when I first got it

 

[L31MaxExpress]

Fantastic ac too, best I've ever had. I was getting 38f air at the vent in 110f heat when I first got it

Same as my Express van when it was newer at highway speeds anyway. Always ice cold with a properly performing system especially after GM put the 11 bladed fan and matching clutch on it back in ~1998 after numerous complaints from my dad that the ac sucked around town and the engine ran hot.

I will say though my mom's 2019 Titan has the quickest cooling, coldest factory AC system I have ever been around. On a 110F day it will hold upper 30s at IDLE with the blower on highest speed. Within a few miles you are knocking off recirculate because it gets so cold on your finger tips. The condenser in that truck is HUGE and it uses an EV fan clutch with a massive clutch fan. When the ac is working hard to cool the heat soaked interior the clutch fan roars in it even with a cold engine.

 

[rob249]

Same as my Express van when it was newer at highway speeds anyway. Always ice cold with a properly performing system especially after GM put the 11 bladed fan and matching clutch on it back in ~1998 after numerous complaints from my dad that the ac sucked around town and the engine ran hot.

I will say though my mom's 2019 Titan has the quickest cooling, coldest factory AC system I have ever been around. On a 110F day it will hold upper 30s at IDLE with the blower on highest speed. Within a few miles you are knocking off recirculate because it gets so cold on your finger tips. The condenser in that truck is HUGE and it uses an EV fan clutch with a massive clutch fan. When the ac is working hard to cool the heat soaked interior the clutch fan roars in it even with a cold engine.

I put an 11 blade on as well when I swapped the motor

 

[east302]

I will be adding two pusher fans in front of the condenser, once I get some more idle amps from the ad244. I am aware that GM used a valve on later trucks, not sure how that system works though. Does it shut off flow or bypass? Where does it bypass too?

If it bypasses from the inlet hose to the return, it would need two shut off valves, which would seal off the heater core.

It’s been a few years since I looked at it disconnected, but I think it connects the inlet to the outlet flow on the engine side of the valve…the same as looping the two hoses together.

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[rob249]

Does that valve operate electrically?

 

[someotherguy]

Does that valve operate electrically?

Vacuum, by the truck's HVAC controls (when equipped with this feature.)

Richard

 

[Erik the Awful]

I will say though my mom's 2019 Titan has the quickest cooling, coldest factory AC system I have ever been around. On a 110F day it will hold upper 30s at IDLE with the blower on highest speed.

That's good to hear. When I was a Nissan tech back in the late '90s, we had customers who would buy a brand new black Nissan Maxima and then complain the A/C wasn't working. Dude, you bought a black Maxima in Oklahoma. The windows aren't tinted, you're leaving the sunroof shade open, and you're parking in the middle of the Wally World parking lot with no shade around. Then you jump in with the windows all the way up and you're expecting 30* air immediately? But they weren't wrong. I think the A/C systems were sized for Hakkaido, and not the American southwest.

The factory manual said to park it in the shade for half an hour, then turn the A/C on and run the engine at 2000 rpm. After ten minutes take a temperature reading from the center vents. It should be 40-45*F. Every one of them passed, and we'd have to show the customer the procedure in the manual and the thermometer in the center vent. They'd get pissed and we'd tell them to go down the road to Don Evans Window Tint. That dude should have bought us lunch with how many customers we sent to him.

 

[OLD BLUE 88]

My truck originally had the bypass on it, didn't seem to work well. Took it off and installed a manual shutoff valve. I was concerned about possible issues w lack of circulation, so I fashioned a connector to join the hoses, and plug the heater core ports to keep bugs out during AC season (which is most of the time here in TX).