atgordon

We have been having a number of strange issues since the motor was removed for rebuilding and reinstalled.

We had a DTC for low Freon, so had the AC serviced and now we get lots of cold air. But no HOT air!

The car is a 94 with electronic climate control. I have undertaken the following steps:

Check vacuum connections at the manifold. All tight and no obvious leaks (got good vacuum at the cruise control module).

I removed the fan control module and looked at down the hole to observe the blend door ... it moves from cold to hot positions smoothly, and in line with the temp. settings.

Heater hoses are new: top hose is very hot, and lower hose seems to be noticeably cooler.

Checked for codes on the climate control system: got the following;

0 = 00 (no faults)
01 Temp Setting = 86
02 In Car sensor = 132 (not sure what this is telling me!)
03 Outside sensor = 85 (?)
04 Sun load sensor = 197 (?)
05 Ign Voltage = 105
06 RPM = 1225 rpm
07 speed = 0
09 mode = 04 (heater)
10 Blower PWM = 66 (not sure what this means?)
11 program = 155 (hot?)
12 mix number = 00 (is this cold?)
16 coolant temp = 80 deg C
17 solar corr. = 124
30 stored full hot value = 54 (?)
31 temp door travel range = 162 (?)
34 temp door position requested = 00 (fully hot?)
35 compressor on = 00
36 times below critical time = 00
37 software version = 14

Any thoughts or suggestions would be great! Tony

pcolt94

Most likely the heater core is clogged. You need to do a flush by removing the hoses to the core and flushing it. One hose goes to a plastic connector and the other the surge tank.

Flush it both ways till it runs clear. Use a garden hose but do not use too much pressure. First time I did mine 7 or 8 years ago it took me about 10 times both ways till it finally ran clear.

GREGGPENN

Or, maybe your blend door is stuck in the cold position?

atgordon

Good call Pcolt ... it was blocked. The first two flushes (one in each direction) produced a lot of brown jelly-like crud (Dexcool legacy?). And, you were right, it takes a lot of straight and reverse flushes before I was getting just water without any bits.

Water flow through the core was quite slow at the conclusion of the process (but still more than then the first two flushes!) but still less than the hose when it was not connected to the heater core. I was very nervous in case I over-pressurized the system with mains pressure city water, so kept the pressure low.

Once everything was hooked up, I was getting lots of hot air, but I might repeat this process next spring after she comes out of hibernation in Michigan to see if I get any more stuff out at that time.

pcolt94

Good job, success always feels good.

I don’t think my car had the greatest of care before I got it. After I flushed mine I had the same problem within 2 years so I did another flush.

End of the story is I flush mine every year before winter and when I change the coolant or it will clog again. So I just stay ahead of it and it keeps working fine. There just must be a lot of stuff in the block and it clogs the core eventually.

Not brave enough years later to NOT flush it and see if it will clog these days. I don’t want to be flushing it in the dead of winter when you need it most.

atgordon

Good advice that I plan to follow!