ColinB

Cape Town South Africa. High summer. 100 deg F. is common. The A/C seems a bit feeble. I take it to an A/C workshop and ask them to top-up the (R12) gas. Hasn't been done for 3 yrs. No problem I think. WRONG.

I get it back an hour later. Blast Furnace. The A/C now no longer works at all except for the faintest feel of cool at max left control lever and even the ambient air flow with the fan off is unbearable. I have to drive with both windows and sunroof open. According to the (usually reliable) workshop the A/C is working normally but the heater is also on.

I reckon this is a vacuum control problem. Don't know why it happened as soon as I topped up the freon. However, I can't drive it like this. I intend to pull out the dash and centre consol this winter for upholstery repairs and could get into the A/C then. In the meantime how can I turn off the hot water supply to the heater matrix for a few months without screwing it up? I have in mind to install a quarter-turn shut-off valve in the heater supply line until I fix it properly. Will this work and where should I install said valve?

TIA

Colin

Lizard928

ok this is a common issue, check the archives, do a search, and find the e-mail keepers,

it is possible to be the heater valve yes, might as well replace

Jim bailey - 928 International

Colin your car already has a heater valve it is held closed by vacuum . When it fails (rubber diaphram splits or it is getting no vacuum ) it allows water to flow through the heater core . The heater valve is under the aircleaner housing at the rear of the engine near the firewall . You can twist the vacuum pod slightly to the left unhook it from metal bracket to pull shut the lever which stops the water . Simply wire it in the closed position . If it is a vacuum problem then the outside air intake at the base of the windshield is probably open sucking in hot outside air as well .

Big Dave

Yep, a heater valve issue.


Here's a link to give a bit more info.....thanks to Tony again!

Heater Valve

Garth S

Before you wire the heater valve open, follow through on Jim's lead - check for vacuum at the heater control valve. As you've had a 'wrench' working on the AC system, follow the principle of 'what/who/w... was changed last? You may well find something left disconnected.