Lukewarm Heat

Hi all,

We're probably all tired of reading posts about little or no heat.
It's amazing how our heaters go out only when the temp falls to zero!

I read all the prior posts but didn't see my issue described: '95
Caravan, 3L, new waterpump/thermostat this past summer. Heater core
hoses pretty hot, top radiator hose REALLY hot, but the lower hose is
ice cold. It heats up, but takes forever, and the air gets hotter as
you step on the gas.

Any ideas?

Thanks
Rick K

 

Sounds like air in the cooling system. Try bleeding the cooling system
thoroughly. You may have a hose collapsing also. Sorry to say this is also a
symptom of blown head gasket(s) which is quite common on the mitsu motor.
Larry

 

Sounds like air in the cooling system. Try bleeding the cooling system

Larry,

Thanks for the reply. A blown head gasket would be too easy!!!! Not
getting any of the symtoms of that, however. I never really paid
attention to the heater when I replaced the waterpump, since it was
summer, and all I wanted was ice cold air.

I'll flush it and bleed it out, and see what happens.

Thanks
Rick K

 

Is the radiator full? I had something similar happen to me.

 

Yep. Only thing funny, is that I run the thing for a half hour, and I
can snap the radiator cap right off, no pressure buildup.

 

That's odd. My guess is that you have an air pocket somewhere in the
system. I'm not sure about yours, but one some cars there is a bleeding
procedure you must follow to make sure there is no air in the system.
You may want to check your owners manual to see if there is any mention
of this.

 

Could be the new thermostat is defective also.

 

Try this, if it's not too late, feel the temperature of the 2 water
lines feeding the heater core as they go through the firewall, when
engine is at normal temperature. They should feel "hot". If this is so
I had a similar problem on my 90 Caravan. The "flap" that moves when
sliding the temperature control from hot to cold was semi seized, and
the cable was just bending. When sliding the lever from hot to cold,
back & forth, you should hear the flap making contact, "thunk, thunk"
against the stops.

Mine was not, ripped out the whole dash and a few drops of oil and
marine grease fixed the problem. However....there is a much easier way
that I discovered afterwards, I will explain in detail if this appears
to be your problem. Condensation from the air con corrodes the spindle
bushing over time.

I noticed your comment on the lower rad hose being ice cold. Strange,
unless your rad is really efficient? What does the your temperature
gauge say?

Good Luck.

 

"Derek"
|
| >Hi all,
| >
| >We're probably all tired of reading posts about little or no heat.
| >It's amazing how our heaters go out only when the temp falls to zero!
| >
| >I read all the prior posts but didn't see my issue described: '95
| >Caravan, 3L, new waterpump/thermostat this past summer. Heater core
| >hoses pretty hot, top radiator hose REALLY hot, but the lower hose is
| >ice cold. It heats up, but takes forever, and the air gets hotter as
| >you step on the gas.
| >
| >Any ideas?
| >
| >Thanks
| >Rick K
|
| Try this, if it's not too late, feel the temperature of the 2 water
| lines feeding the heater core as they go through the firewall, when
| engine is at normal temperature. They should feel "hot". If this is so
| I had a similar problem on my 90 Caravan. The "flap" that moves when
| sliding the temperature control from hot to cold was semi seized, and
| the cable was just bending. When sliding the lever from hot to cold,
| back & forth, you should hear the flap making contact, "thunk, thunk"
| against the stops.
|
| Mine was not, ripped out the whole dash and a few drops of oil and
| marine grease fixed the problem. However....there is a much easier way
| that I discovered afterwards, I will explain in detail if this appears
| to be your problem. Condensation from the air con corrodes the spindle
| bushing over time.
|
| I noticed your comment on the lower rad hose being ice cold. Strange,
| unless your rad is really efficient? What does the your temperature
| gauge say?
|
| Good Luck.

We had a similar situation with a GMC S-10 turned out the heater core was
blocked. Take the return line off and run the engine to see if there is any
outflow on the low side. (heat control full on)

We found that taking both lines off and back flushing the core improved
things greatly but ultimately we had to replace the core.

 

Good point. The good old "Reverse Flush"