Well i did the search thingy first.Found some general stuff.Oh BTW thanks for this great forum.

My question,i have 2 volvo wagons both 240's.One is a 86 the other a 90.
Im having trouble with the defrost only.

I dont have any coolant leakage.In or out.The blower is fine,makes some noise at certain speeds.Man oh man on both of them the heat works just fine itll blow me away.
The only problem is on both of them it doesnt defog the winshield.
I can feel a slight amount of air coming out the defrost when the fans on high.But on the feet and mid section the heat just pours out.

No matter what selection i use,i have 3 of them no defrost.The heat selector is in the middle just above the pull out ashtray.

I looked in a manual and it gives me general info.

Please give me some specifics.Thanks in advance to anyone who can help.

Can i just open the defrost vents up somehow and leave them open?Would that be ok?
I live in Seattle so it doesnt get real cold too much just lots of moisture from rain.

 

I'd start by checking the vacuum lines that control the vent directional flaps. Over time, they deteriorate and are unable to hold a vacuum, thus not closing the flap fully. Look for dry rot, or any melted areas.

 

Thanks chipmink.
Well i guess i should drag my lazy butt out there and pull the dash apart and look around....lol.

Im not sure this is correct but i saw something in the forums where a guy fixed his cruise control while,working on his heater issues?My cruise control sputtered for the first time this summer,it wouldnt barely work.Now the defrost on the 86 doesnt work.hmmmmm

On the 90 the cruise works great,the defrost doesnt.I guess im just going to have to learn how to work on my cars dagnabbit.

Ok ill go fiddle with it.The suns shining here in seattle so its a good reason to go outside.LOL

Thanks for any input from those who know.

 

Ok i took the glove box out,i took the radio as far out as i could without disconnecting it.That was easy enough.Taking the center console loose was ok,but i could see where it could be a hassle.I didnt do the instument cluster.Couldve but didnt.

I was able to see the defrost flap control from the glovebox compartment area real good.The drivers side was visible slightly from the radio compartment.

All the hoses looked attached and in good shape at the flaps and where they went into the heater control switches on center console.They actually looked new.

Then i pushed the three buttons for the defrost,heat and recirculate.

When i hit the defrost i could see the little actuator(diaphram) try to move the flap open(sucking in) but it just couldnt do it.Same way on the heater button.

I could manually push the actuators and they worked and were not sticking.


I took the springs attached to the flaps off,this allowed the vents to remain open.Soooo thats where ill stop.I get enough air to all the heater vents and the fan/blower/heat work just fine.So i can control the heat by the fan switch...i loose control of wich vent i get it out of.

Also with the springs off the actuators/diaphrams actually work wich shows me it is just eaither weak vacum or something else.

However its a work vehicle so it defrosts the windsheild so you can see driving down the road.

I suppose its the vacum pump or something on the heater unit that isnt functioning properly.So ive detailed it for others who might read this.It took about a half hour.GL.

************** i guess my question to those who know would be does the heater core have its own vacum pump? or does the vacum come from the main engine vacum pump? I guess i need to know if this will effect other parts of the vacum process other than the heater?********************

Thanks for a great forum and any answers and insight.

GL

 

there is a vacuum tank in the center console for the heater controls if you remove the left kick panel on the passenger side you should see it and it comes from the engine