Hot coolant and suffering AC

[TTait]

OK, one of two things is happening...

Its hot here - not Phoenix hot, but 115-125 on the freeway - still, hot. My AC is blowing cold when I first pull out of the garage, I'm getting low 30s out of the ducts. Then as the car warms up, it gets warmer, once the coolant gets really hot, and its been getting up to about 225 on the gauge, the AC can barely muster 70 degrees.

The pressures all look pretty normal, but the air should be blowing colder.

Either as the radiator gets hotter its passing heat on to the condenser, or my heater core is getting hot. I recently realized that the cut off and crimp sealed plastic vacuum line coming out near the CPR is supposed to extend to the heater control valve... instead nothing is hooked to the heater control valve.

Now either - my car has been circulating heat to the heater core for 5 years and I never noticed (unlikely?) or the hot radiator (3 year old Hervey) is really heating up the condenser. Should I consider unbolting the condenser from the radiator and install longer bolts and some washers for spacers?

I wasn't planning on worrying with hooking the vacuum line until winter - unless thats where my problem lies...

Suggestions?

[Bitsyncmaster]

Are you running on MAX? If not then what your reading 70 deg in extreme heat and sun would sound about right.

You defiantly want to get the vacuum line fixed to shut the heat off when running MAX. It will help but I've only seen 3 to 5 degrees colder. Your condenser is in front of the radiator so when your moving it should not be affected by the engine heat.

[content22207]

Just bypass the heater core with a short piece of 5/8" hose (either behind the engine or behind the accumulator) -- that will tell you quickly and inexpensively if the heater core is the culprit.

Bill Robertson
#5939

[dmc6960]

Are both cooling fans blowing the right direction? If hooked up backwards and one or both were pushing air forwards, it may work decent still while stopped, but would really fight with the airflow going down the freeway.

[David T]

Make sure the condenser and radiator are not plugged up and air is easily passing through them. Make sure both fans run, run in the right direction, and the fan blades are firmly attached to the fan shafts. Make sure the cooling fan circuit breaker is not popping and resetting. For the A/C to work properly the engine cooling system must be running properly. Make sure you have 50/50 soft water and anti-freeze. The system is full and bled of all air (header bottle 1/2 full when cold). Test the pressure cap. Make sure nothing is blocking the inlet of the pressure duct to the radiator (license plate etc). Check that the Vee belt to the water pump and alternator is not slipping. If the motor was ever overheated and you popped the head gaskets that would cause the motor to blow out coolant and overheat.
David Teitelbaum

[TTait]

Cool - I'll get started on the list - thanks guys.

Can someone confirm for sure whether no vacuum at the heater control valve would give me full heat or no heat?

[DMCMW Dave]

vacuum = off, no water flow. You can t-tap it into engine vacuum and then you won't be opening up the cooling system.

no vacuum = on, i.e. water flows.

[TTait]

I only need to extend it 18" - it makes it into the engine compartment and then it looks like it was cut and hot crimped together. I just need to come up with Vacuum hose of the right size (???) and get my hands down to the heater valve.

That is, if the control in the dash still works...

Thanks guys...

[Bitsyncmaster]

I only need to extend it 18" - it makes it into the engine compartment and then it looks like it was cut and hot crimped together. I just need to come up with Vacuum hose of the right size (???) and get my hands down to the heater valve.

That is, if the control in the dash still works...

Thanks guys...

It's a really small ID hose that will stay on the heater valve.

[TTait]

yep, the smallest Pep Boys had.

I wish every fix was that easy. Less than $3 and it took about a minute. I can tell the valve is working now as the air flow changes and it gets hot when i turn it to heat and cool when I turn it to cool (while on vent).

Yesterday the AC temp went up about about 50 degrees once the coolant got hot. Although I have not been on a drive yet I'm guessing the AC will work a lot better without the heat cranked too.

I actually thought the AC did ok on the drive to Vegas for DCS West two years back, despite the heat having been on in the car for the last 6 years.

I'm further guessing that even on max AC I'm still getting significant airflow through the heater core, and I suspect that should be sealed off by flaps in the air box. Sounds like that ought to get fixed someday too...