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That is NOT how they're advertised. Lots of folks--including, apparently, the folks retailing them--are afflicted by a lack of logic and an excess of wishful thinking. I see this statement fairly often in regard to the "Failsafe" thermostats.they talked me into this “failsafe” brand. Supposedly if it fails at all it will stick open no matter what.
When overheating is caused by a deteriorating cooling system part, the fail-safe has a secondary stroke that activates a precision engineered piston. This automatically locks the valve into a wide open position to allow coolant to circulate freely.
Note that once the fail-safe thermostat has locked in the open position, it cannot be used again and must be replaced.
Yes. When it fails. But there's no reason to replace it "just because".Think I should change it out?
That lead me to looking at the heater hoses, theres a little valve right before the fire wall with vacc lines running to it. I found a vaccum leak there, fixed it and still no heat.
That valve applies vacuum to shutoff the flow to the heater core at the crossover valve, when you turn on max A/C. Unless max A/C is on, it should be fully open. the vacuum line should run to a solenoid on the firewall and then on to the intake. I don't think this is the issue. Make sure you have a 195 T-stat, I tried a 180 in my Suburban and just couldn't get it hot enough.
Did you bleed the system after installing the thermostat?I forgot to add the t-stat is about a month old.
I did bleed the system, it got a new radiator at the same time. And didnt have issue with the heat until i replaced the climate controls, blower motor, and resistor. But ever since monday morning it blows good and hot so who knows whats goin on i havent changed anything.Did you bleed the system after installing the thermostat?
On the actuator, the notched silver dial rotated smoothly between (roughly) the 11 and 1 o’clock positions? There should be marks on the housing that correspond.
Adding to what the others said on the valve on the heater hoses, there’s a rod/plunger at the bottom of the valve which is connected to the valve butterflies. Engine on and temperature set to heat, push up and down on it and it should move with moderate pressure. Compare to engine off and the effort required should be pretty damn close if not the same.
When the valve is closed (panel temp dial is set to MAX detent) the solenoid is energized, vacuum is applied and the rod is up or pulled inside of the valve. It won’t move.
The valve is specific to Tahoes and Suburbans, closing when the “max” detent is selected on the temperature dial. Alternately, pull the vacuum hose from the valve and see if it makes a difference.
If it does or if that plunger doesn’t move when the dial is not set to max, then the solenoid valve on the firewall may be energized somehow which goes back to the panel itself. See if you have 12V on the connector to it in that case. You shouldn’t unless it’s set to “max”. I’ve had a (dorman dirty word) panel that was brand new and kept that thing energized regardless of what it was set to.
If the valve is closed and you don’t have voltage to the solenoid or if that plunger doesn’t move with the engine off, then I’d suspect a bad valve.