hello, I replaced my t-stat on my duratec cause my temp Gauge was pegged on cold and I had just barley warm air with max heat selected. Mine didn't have the sensor on it so it was only 28$ After I got everything put back together I refilled the pressure tank and the engine didn't want to take the antifreeze it eventually sucked some in I had to drive around with the cap loose before I could put anymore in , I finally put as much in it as I took out but the level was low when I started and the pressure tank is full right now so I'm assuming I still have some air pockets in my system ?? My gauge reads right where it should now a little under half but when I'm just idling my heat goes cold/warm when I'm on the gas it's hot. I pulled the vac hose off the valve under the hood with my heat on high and felt no vaccum I remember pulling it off before playing under the hood and felt suction. Any recommendations ?

 

With engine cold and off, remove heater hose from firewall and make sure it has coolant inside.
When refilling cooling system you should remove 1 heater hose to allow air out of that section of the system.
If air is left in there it can cause an "air dam", water pump can't push it out.

Rangers had two different types of vacuum valves on the heater hoses over the years, when AC is off there is no vacuum, coolant is flowing into cab, when AC is on then vacuum is on CLOSING the coolant flow into the cab, so no heat.
And then the opposite, vacuum is present when heat is on and no vacuum when heat is off.