No heat 91 jimmy

very cold out this morning, have water in system, but no heat, only blows cold air.

should i let some water out and refill with antifreeze?

Where do you live??

Antifreeze is NOT just for winter driving…but summer too. Antifreeze also has anti-corrosive additives that prevent rust and also helps lubricate the water-pump. I don’t know of any place or any condition where you’d want to drive with 100% water in vehicle that’s newer then 30 years.

If you have no heat due to the water freezing then you have bigger problems. You really want to unfreeze the water and hope one of the freeze plugs didn’t come out. Drain and refill with a 50/50 mixture of antifreeze and see if that solves the problem. Although I think you have something else going on there.

mostly water at this point, but not 100%, freeze plugs are intact,
and yes, i know that antifreee is for all seasons, but i had a leakage problem last spring so resorted to mostly water 'til that problem was solved…now it’s suddendly gotten very cold here in new jersey… was cold yesterday and the heat worked fine…gonna get some antifreeze, drain and refill…run it and see…

well, after taking the wife to work and then letting 'er set for a bit,
went out to get some antifreeze, etc., and the heat works fine…musta
just been too damn cold, and i may have narrowly escaped a freezing problem…
going to drain and fill with antifreeze anyway, that’s the right thing to do.
note: no leakage anywhere, hoses are fine, temp is fine, whew, that ws a close one.

Sounds like your truck narrowly escaped a one - way trip to the junkyard.

yeah, no kidding…
so far on this truck i’ve replaced the water pump, fuel pump and related, shocks, axles (cv’s included) exhaust (from the cat back) and who knows how many lights and buzzers and all that other nickel and dime stuff. still runs pretty damn good, tho…
when i had the coolant leak prob, turned out there was a pinhole in the hose that came from the manifold to the heater, then she woudl die after running to warm, so i replaced the little brass temp. thing in front of the therm…one thing after another, but i guess i’ll be good 'til spring for now, and i might be getting a '94…another jimmy…another history to be written…