No Heat

[Anonymous_User]

The patient: 1988 Shadow TBI
The symptom: No heat

1.) Patient has had a heart transplant in the past and now enjoys a 2.5l CB.

2.) Patient still sports the '88 vintage water pump, housing, pully, accessories.

3.) Now with a new t-stat, patient has good coolant flow through engine and temps stay steady at 1/2 gauge.

4.) Patient just received a mixing-valve-ectomy. Heater core lines now go from head -> intake mani -> heater core -> water pump.

5.) Supply line to heater core hot. Return line not so hot. With heater blowing cool air inside and set to hot.

6.) Compressed air through heater core moves coolant easily.

7.) Can hear flapper door closing when temp slider moved from cold to hot rapidly.

At this point I think I'm ready to pull the dash and drop the heater box out for exploratory surgeory. Comments?

[jamesmonty]

Try a little CLR to clean it out? That's all I could think of other than something under the dash.

[Tony Hanna]

5.) Supply line to heater core hot. Return line not so hot. With heater blowing cool air inside and set to hot.

Ideally that would be what you want. The coolant enters the core hot, sheds it's heat into the car, and then exits cooler. With it blowing cold air though, it sounds like there's not enough hot coolant making it through the core to affect the air temp. My advice would be to first check for a restriction in the core with a garden hose (don't know what kind of volume you had when air checking it). If the core flows water good then check for any restrictions in the lines. If that fails, then I'd try to bleed the cooling system at the point where the return hose attaches to the heater core so you can be sure you don't have an air pocket causing trouble. I'd try all that before ripping into the dash.

Also, with the engine warmed up if you raise the rpms and hold it steady for awhile (3000-3500) does the heater start to warm up? That would point to a definite problem with air trapped in the system.

[Anonymous_User]

My advice would be to first check for a restriction in the core with a garden hose

Also, with the engine warmed up if you raise the rpms and hold it steady for awhile (3000-3500) does the heater start to warm up? That would point to a definite problem with air trapped in the system.

1.) No garden hose access until temps creep above freezing. Could be a while.

2.) Didn't compare heat output with RPM. Will try soon.

[mo' parts]

what about the hot/cold selector switch? doesnt it run a dampner that switches between the heater core and evap. coil? i believe they run on vaccum in these cars. (not too familiar with that area of these cars, lol)

[Anonymous_User]

what about the hot/cold selector switch? doesnt it run a dampner that switches between the heater core and evap. coil? i believe they run on vaccum in these cars. (not too familiar with that area of these cars, lol)

Nope. That is cable driven, not vacuum driven.

7.) Can hear flapper door closing when temp slider moved from cold to hot rapidly.


Either the core is plugged and not flowing enough fluid, or the Flapper is not coming close to sealing. Gonna need another weekend.

[mo' parts]

thanks for the info, sorry i missed that one..
Definitely sounds like a restriction in the core then.
Im curious as to how hard it is to replace the core as my 87 needs one.

[stereo]

The first thing I would do is flush the system. there's no need to use any special chemicals. If you can get a metal rod with a connection for a hose that you can fit in side the rubber lines that would be great. Just undo the hose from the head and the water pump, stick in the pipe to one of the hoses, turn the hose on high and it will blow all the crap out. If it flows like a normal hose out of the other end then there's no clog. When the water comes out clean then your good and just swap it to the other hose and go the oppisite direction. If nothing flows the first time swap to the other line and try. I had that happen when I did my van. It had the same problem, Now the air so hot I can't leave it on too long.

Another thing to if your not using A/C for a while or good if you deleted the A/C all together is to bypass the heat proportioning valve, the black plastic or metal vlave that the heater hoses go to before the heater core. This helps free up flow and helps the coolant flow through the core more constant.

And the last thing is to remove the blower motor from the dash And check to make sure there's no debris clogging the flow of air through the heater core, which is right to the left of the blower motor and easy to fit your hand in to check. Also make sure there is no gunk in the fins blocking air flow through them. And if your blower motor doesn't blow too hard, this should help free it up some, but if there was no clog, then while you have it out you may as well replace the blower motor with a stronger one.

Thats about it. Those three things are about the only things you can do to have a kick --- heater. And there is no reason to removoe or replace the heater core unless it is leaking, Which you would notice. When I got both my cars the had no heat at all and by doing these three things the car heats up in no time.

[black86glhs]

The first thing I would do is flush the system. there's no need to use any special chemicals. If you can get a metal rod with a connection for a hose that you can fit in side the rubber lines that would be great. Just undo the hose from the head and the water pump, stick in the pipe to one of the hoses, turn the hose on high and it will blow all the crap out. If it flows like a normal hose out of the other end then there's no clog. When the water comes out clean then your good and just swap it to the other hose and go the oppisite direction. If nothing flows the first time swap to the other line and try. I had that happen when I did my van. It had the same problem, Now the air so hot I can't leave it on too long.

Another thing to if your not using A/C for a while or good if you deleted the A/C all together is to bypass the heat proportioning valve, the black plastic or metal vlave that the heater hoses go to before the heater core. This helps free up flow and helps the coolant flow through the core more constant.

And the last thing is to remove the blower motor from the dash And check to make sure there's no debris clogging the flow of air through the heater core, which is right to the left of the blower motor and easy to fit your hand in to check. Also make sure there is no gunk in the fins blocking air flow through them. And if your blower motor doesn't blow too hard, this should help free it up some, but if there was no clog, then while you have it out you may as well replace the blower motor with a stronger one.

Thats about it. Those three things are about the only things you can do to have a kick --- heater. And there is no reason to removoe or replace the heater core unless it is leaking, Which you would notice. When I got both my cars the had no heat at all and by doing these three things the car heats up in no time.

You are correct, but the CLR helps to break up some of the contaminants in the core. He has already eliminated the bypass valve and run the hoses directly. The fact that he has hot in and luke warm out and still has little heat, means the core is partially blocked.

[raccoon]

if you have the 185 thermostat replace it with the hotter one, night and day difference in temp.

[looneytuner]

You can also reverse the two hoses at the core to help unclog it temporarily. Of course you still have the crud circulating in the system.
If it's any comfort, the new heater cores are twice as big so you will have LOTS of hot air.
]
A full pressure garden hose has about 7 times the pressure that the system was designed for!!!!!

[tsiconquest88]

i cant get heat with the 185 i got now or the OEM lol. I had wrote about this and i decided to take the reverse flush and all, just havent done it yet. I think thats where your headin anonymous. Seems kind popular of posts with people having no heat. Certainly cant hurt.

[stereo]

Also when fill it back up with coolant use distilled water. This will help the core from getting clogged with contaments brought on by tap water.

[tsiconquest88]

Sounds good to me lol