I posted this under "Heater Core Shutoff - Does it work?". It didn't get much play on page 3 of the thread, so here goes again.

Original post-

Ok, all these posts are jumbled up in my head, let me see if I've got things straight.

The other valve is a simple on & off valve with no re-routing coolant back to engine, but the AutoZone valve does re-route. Does the coolant really need to be re-routed to the engine??

Tapping into the red vac. line cuts off heat on Max A/C, A/C, and Vent positions. The white vac. line cuts off heat only on Max A/C. With both vac. lines, heat is still on in all other positions. If I did the red line...will the A/C be freezing cold all the time regardless if I raise the temp ****?

Does the kit come with the T-fitting, vac. line, and hose clamps? What are those extra fittings on the bottom of the picture for? I took a look at the vac. lines behind the dash and tried to remove one of the vac. lines from the 'cluster'. Mine looks a little different than Abendx's, it has clear plastic encasing the lines to the cluster, the same plastic thats on the blue and yellow lines in Abendx's pic. I pulled like heck on the red line and it didn't want to come loose...is cutting the vac. lines to install the tee an option?

I really want to do this mod, living in Texas heat is bad...but I've got wetland humidity ontop of Texas heat!!

On another note...does anyone remember the fix for the A/C compressor cycling on and off every 15 seconds?? I seem to remember Monsta having a fix dealing with the spacing of the plates on the compressor, but I can't find it anywhere!

 

I went to the site that has the heater control valve kit and after ordering it with shipping it would cost me $36. I went to Autozone and purchased the same valve for $10. Also bought an inexpensive tee and a good length of small hose. $17 looks a lot better than $36, and I don't have to wait for shipping (2 weeks). I have a '99 V10 so it didn't match the pictures that were posted. I cut mine just after the straight bend to the firewall on the right side hose. The valve from Autozone fits perfect. You just have to unbolt the assembly/bracket that is bolted to the top of the a/c housing (3 11mm nuts on studs). The hose I'm running tomorrow, it's raining already here, but looking forward to some colder a/c. The heater valve from Autozone is #74612 (Factory Air). I looked at the valve that was mentioned on this forum, but it has 4 hose fittings that would require a lot more work. You don't want to reroute the coolant, just stop it from flowing. My heater lines came out of the firewall about 12" and then enlarged and bend down to 2 metal lines on the back of the motor.

 

This mod has been around long enough that there should be someone who can answer this...

Has there been any problem with corrosion or other damage to the heater core with no coolant flowing through it?

I plan to go ahead with this mod, but I would hate to turn on the heat next winter and have wet carpet.

Scott

 

>>>The other valve is a simple on & off valve with no re-routing coolant back to engine, but the AutoZone valve does re-route. Does the coolant really need to be re-routed to the engine??

Well no but it allows the coolant to circulate through for engine cooling.

>>>Tapping into the red vac. line cuts off heat on Max A/C, A/C, and Vent positions. The white vac. line cuts off heat only on Max A/C. With both vac. lines, heat is still on in all other positions. If I did the red line...will the A/C be freezing cold all the time regardless if I raise the temp ****?

I do believe you are trying to make it colder right? All you are doing is tapping into the vaccum line to actuate the valve. If you do either valve you will not be able to adjust the temp up, since the coolant is rerouted.

I hope this helps, I had my kids complain that the truck was too cold.

 

I have a question in relation to the coolant smell in my vents. Whenever I have the vent fan activitated or Noermal air conditioning I get a burnt coolant smell. I have no leaks and appear to have not lost any coolant. Any suggestions asd to what this might be? I have taken it to the dealer and they pretend that it's normal it of course is not. Help.

2002 F-250, CC, XLT, 4X4.

 

I shared your concern about shutting off the flow vs rerouting it and delayed purchase while I gave it deep thought (well, deep for me) In going back through posts on the subject I didn't see any hard evidence of a problem, only theory. Plus I figure the mod has been out long enough that any problems with shutting down the flow would have been reported. I went the simple route with the cut off valve that fits on one hose. Less connections which is a plus. Can't believe that coolant sitting in the heater core would cause problems but around here a person doent run air cond from April to Nov withhout shutting it off like in some parts of the country.

 

I can believe that letting the coolant sit in the heater core for a long period of time might cause deposit build up. I base this on the 88 Dodge Caravan that I have, which has a heater core shutoff valve. During the Summer when we have the AC on all the time the heater core is shut off. I have had the coolant flow almost completely blocked by buildup in the heater core. Fortunately I caught it in time and was able to backflush the heater core to clear it out. A neighbor had his Caravan heater core blocked solid and had to replace it.

I don't know if the same applies to the Superduties but I am not taking any chances. I installed the bypass type system. I am planning to install a solenoid vacuum switch so I can turn it on and off at my discretion. I like this better than tapping into the vacuum system (the red vacuum line) because I want to be able to have heat come out of the dash outlets while in AC mode. I use this setting in cool but damp weather.

I will post the part number to the vacuum solenoid switch when I get it. The local AC shop told me they had them for about $7.

 

Thanks Pete,

This is the approach I was looking at taking when doing my as well.

Jeff

 

Guys I'm interested in this mod as well but what I really want to do is have cool "vent" air so I don't have to run the AC as much. Of course I'll need switch or something so I can get my heater back. Can someone please clarify hor to do this and what parts i would need?

 

I believe that the evaporation drain may have been plugged. I just back from a trip to Phoenix (from Las Vegas) and the smell appears to have disappeared and the evaporator drain is working again. (I ran the air the whole trip.) Hopefully this is it, however I will keep watching and if I have any other new occurences or info I will post. My Mechanic told me to inspect the head gasket for slight leaks and I found nothing.