Rear Heat

[ZiLLa]

Have blower & it work in the rear, but no heat, wheres the lines hook up at.....anyone have a GM schematic?

[satrunsc2]

i think they hook up behind the driver seat or at the left of rear doors

[ZiLLa]

From the previous owner,the water pump was replaced twice,just curious if that was the leak & not the WP.....he had it since it was new, i'm now sitting on 110k......

[Lumpy]

Have blower & it work in the rear, but no heat, wheres the lines hook up at.....anyone have a GM schematic?

I think(?) you're saying the fan works, blows air, but it's not hot. Yes?

Look for the dreaded hot water/heater bypass valve. It has several names. It's the topic of a lot of frustration right here on this forum. Find the two hot water lines that connect to your rear heater, under the van behind the driver seat. Those two lines are metal 3/4 inch OD in some places, rubber 3/4 inch ID in others. The metal portions of the lines insert to the rubber portions. They go through the floor from under the van into the heater. Follow those two lines forward, toward the engine. They will cross OVER the transmission and eventually lead to a black plastic multi-armed "tree" thing with several similar sized hot water hoses connected to it, as well as a vacuum hose.

Mr Maher, sir, please post that pic and describe what ZiLLa should do to deal with said valve.

Normal operation is that this valve thingie opens and closes when you ask it to and allows or dis-allows hot water to flow to the rear heater coil. When hot water isn't making it back there, suspect this valve. It could be clogged. There may be a vacuum leak not allowing the vacuum to activate the thing appropriately.

Probably also worthwhile to ensure that the lines themselves as well as that rear heater core are clean and running water freely. Cleaning old sludgie poo out of all the cooling system helps heating dramatically. I think the rear heat section tends to sit there and not get used a lot. That leads to sediment forming, blah blah. As opposed to the front system which in some year vans, is always "live" and therefore always circulating.

Don't use DexCool coolant. It's proven to be problematic over and over again.

Brush after every meal.


Lump

[Astrodarmiss]

I dislike just saying do a search on this site but I have seen quite a nice write here. Sorry I can't take the time to do it for you to provide a link here.

[redfury]

You will find the valving attached to the side of the heater core housing under the hood. It's location will be on the passenger side of the van, mounted behind the silver cylinder ( dryer/accumulator ). Just look for the mess of heater core sized hoses coming out of it.

The first thing to try is to bypass the solenoid that controls the rear valve. That's just a matter of moving the incoming vacuum line on top, to the bottom connection. If you don't get heat that way, then the lines or valving itself is likely full of crud that will have to be flushed or otherwised cleaned out. The valving I got second hand looked like it had a brown sponge like material in the hoses from god knows what ( possibly a stop leak product ).

[ZiLLa]

No stop leak here,appreciate the responses,this van has had the trans fluid changed every 5k as well as the oil every 3k,& the coolant system there between,probably a vac line....will look into it & post........wasn't looking for sarcasm,the van has 110k.....& serviced religiously since 10k.....new tires , brakes,AC, water-pump,fuel pump...& & after this most ;likely your girl friend....care to **** with me more????

[ZiLLa]

Thanx RdFury........it should only be a vac line though, or the valve as you said,will check & report so that others know.

[Lumpy]

...wasn't looking for sarcasm,the van has 110k.....& serviced religiously since 10k.....new tires , brakes,AC, water-pump,fuel pump...& & after this most ;likely your girl friend....care to **** with me more????

...

What?


Lump

[techman1]

You have rear AC but not rear heat. There is only an AC evaporator coil in the side wall and the lines come in from underneath the van. That blower just pulls air through the ac coil in the side wall.

[redfury]

You got me lumpy... Not sure what that means or who it was directed at.

[Leeann_93]

This is a family board; we do try to keep profanity out of our posts. Thanks for understanding.


Second, if you have rear heat, the switch is in the middle of the 3 panels to the right of the front AC/Heat controls. Rear AC is the top switch.

Third, the diagram and parts are available from gmpartseast.com:


There are photos of my rear heat assembly and the pipes going to it in my New '99 Safari thread in the uncategorized section. I haven't had to do anything with the water valve yet.

[ZiLLa]

Thanx for the replies & sorry for the profanity,(& that wasn't directed at anyone,just my sick sense of humor)........& mine only has rear heat as far as I can tell,& I know where the switch is LeeAnn,what I'm saying is when switched on the blower engages....but no hot air,there is not a A/C switch just heat.& sorry if you took that the wrong way lumpy..LOL

[Leeann_93]

Pop off the cover over the rear heater core & blower - one screw on the driver's pillar, then GM's brilliant idea of pop clips on the rest (just be careful not to break the plastic posts). With the van running and plenty of heat at the front, feel the rear heater core. Is it at all hot? Only at the bottom, only at the top, etc?

If the rear core is cold, slide under the van right where the core is. The metal lines end in molded hoses that connect to the rear core with regular hose clamps. Have a bucket ready and check for coolant to the core. If no coolant, you need to check the water valve thingy. If you do have flow, I'd stick a hose in one pipe and see if you can blow chunks out. If none, stick it in the other pipe and see. If no chunks, then check the water valve thingy.

[ZiLLa]

Thanx LeeAnn,I'll check as soon as the weather gets better,its not really a necessity,but bothers me when stuff don't work like its supposed to.

[ZiLLa]

Never mind,loose vac line on the actuator,(or valve thingy)LOL all rear vents blowing warm now,& thanx tech ,you were right it has a evap in the back too...will freeze meat back there......Thanx all for the replys....& Thanx for a great & informative site.Now to tackle the fog light scenario....