Uh....ok....I reckon it's there for a reason.

[69 Okie Truck]

Was checking out my heater hoses and saw this diaphram wedged onto the lower heater hose.....
Any idea as to what it is or why it's there? I don't remember ever seeing anything like this on any of my other trucks.

Sorry about the pic. Cell hpone quality in bright sunlight, but you might be able to make it out.

[Shyguy]

Looks like the heater control valve to me. I know some of the air conditioned trucks had them.

Neither of my non a/c trucks do.

[69 Okie Truck]

Well...it's just stuck to the lower line. no vacuum line running to anything. Reckon I could just dispose of it and run straight line there? Our winters ain't brutal, but it would be nice to have a defogger on that windshield.

[Shyguy]

Yep, you could just take it out if you are not running a/c. What it does is shut off the flow of coolant to the heater core when a/c is being ran.

Since it has no vacuum just might as well remove it. I sure don't like to drive a cold truck myself.

[69 Okie Truck]

Thanks....guess I'll pull it until springtime. My A/C blows cold in the old gal, but I ain't got a lick of heat....zip, nada, zilch.

I sure hate wiping the inside of the glass with a t-shirt to be able to see on cold days.

[ls1nova71]

Taking the heater control valve out probably won't help you're not having heat problem. It shuts the water off in "max air" by putting vacuum to the valve, since it's not hooked up to vacuum it should be open all the time. You won't hurt anything to remove it, but I've never seen one stick closed. Are both of your heater hoses getting hot? Or you could just need a new thermostat, that's where the no heat problems usually come from.

[69 Okie Truck]

Thanks guys....took it off and the defroster is kickin' very hot and very well. I gots me sum heat!!!!! Wish all of lifes fixes were so easy.

Shyguy.....I owe you a couple of beers.

Come March I'll re-install it to make sure my A/c is blowin' as good as it was last summer. I know I'll need to figure out what's goin' on with the thing one day, and I did spot a couple of vacuum hoses laying loose that might go to the thing, but for now it'll do. I'm a long haul trucker and don't get but a few days at home during any one stretch and I can think of far better ways to spend them on this stretch than under the hood.

Y'all rock, and I'll cough up the cash today and become a member since I spend so many days on the road in my sleeper on the laptop deriving enjoyment from this place.

[Shyguy]

Originally Posted by 69 Okie Truck

Thanks guys....took it off and the defroster is kickin' very hot and very well. I gots me sum heat!!!!! Wish all of lifes fixes were so easy.

Shyguy.....I owe you a couple of beers.

Come March I'll re-install it to make sure my A/c is blowin' as good as it was last summer. I know I'll need to figure out what's goin' on with the thing one day, and I did spot a couple of vacuum hoses laying loose that might go to the thing, but for now it'll do. I'm a long haul trucker and don't get but a few days at home during any one stretch and I can think of far better ways to spend them on this stretch than under the hood.

Y'all rock, and I'll cough up the cash today and become a member since I spend so many days on the road in my sleeper on the laptop deriving enjoyment from this place.

You are welcome, glad we could help you.

[lowrollin70gmc]

In the spring you can put a simple on off valve in its place so you don't have to keep unhooking lines.