Hello guys,

New to the forum but have been visiting it for a while and it has been very helpful.

I am unsure as to the function of this broken plastic vacuum line (picture attached), and I’d appreciate it if someone can shed some light on it. I suspect it goes to the Heater Control Valve (HTC), as I changed it recently and noticed its vacuum line was also broken.If it does go to the HTC, is it appropriate to splice it with a bigger line or is it advisable to change the entire line with a Ford part?

This is a 1999 Mazda B2500, RWD, 2.5L L4 SOHC 8V (Same as 99' 2.5L Ranger)



Thank you!

 

Yes, heater control valve is where that vacuum line goes. If you can find a similar size line somewhere, they should make a rubber connector for both that way you can just spice it back together.

 

Much Obliged!

 

+1, on the heater ByPass valve, it doesn't control temp in cab, just FYI, its an on/off valve, no in between

And it looks like your bypass valve has been removed, I see the splice in one heater hose
These often cracked and leaked so were just removed and hoses spliced

Bypass valve looks like this: https://www.oilburners.net/articles/pictures/valve2.jpg

2 hoses to heater core(firewall) and 2 hoses to engine, so 4 hose connections
The grey Vacuum line goes to the vacuum valve, on top in the picture

This bypass valve is only used when MAX AC is selected in the cab, it sends the hot coolant back to engine bypassing the heater core so it can't transfer ANY heat into the cab for "max" cooling in the cab

Its not technically a vacuum leak since the line/hose comes from the cab vacuum system which gets its vacuum from vacuum reservoir, so it can't effect engine operation like other vacuum leaks can

You can just cap it, tape or ?? until you decide to replace bypass valve, if you ever do