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I have to say the last time I had the HVAC system recharged was May of 2017 and one the things that I do in the summer and this may help you as well is I disconnect the hoses from the heat exchanger to the chassis flapper boxes, that way you get max cold air, And reinstall in the late fall,
It seems that our cars get old the heat seeps through the front mixing flaps, Because the foam edges that seals the flap starts to go bad. When you disconnect make sure you vent it outwards so that your not blow the hot air on your starter or wires.
I was stopped at traffic light two days ago and my vent temp was at 34F, 90 deg out and 56 percent humidity. my new VW vent temp blow ice cold at 29F. I would like to see how cold you're AC gets. Please share your pic's
Get a standard probe thermometer and show the readings for vent temps. Best I can tell, those IR models don't seem to work as well on this application.
Get a standard probe thermometer and show the readings for vent temps. Best I can tell, those IR models don't seem to work as well on this application.
Ive never had much luck with them ever now that I think about it.
Design evaporator temperature has to be above 32F otherwise it turns into a block of frost. 964 system has a thermistor whose signal is bussed to the Hvac controller, when evap temperature nears freezing the compressor clutch opens for a short time. This is not unlike any ac system somfor this reason discharge air temperature cannot be below freezing. Earlier poster was correct, use a calibrated thermometer. Inexpensive stainless steel probe with dial indicator is about the best for ac work. Check the ice point by plunging the probe into ice/water mix and check for 32F.
Below is the specification from the service manual.
Use a normal thermometer, not an IR-based. Measure at the nozzle, no sun, about 20-25deg C ambient, engine running, max fan speed, minimum temperature setting, resirculation ON.
I measure about 8 degrees in these conditions, and it has been 7 years since changing a leaking evap.
Cheers,
Tore
I just refurbed the entire system in my car (evaporator, condensor, expansion valve, drier, compressor, all new o-rings, new hoses in the engine bay). Here in Texas, with ambient at 90-100-degrees F, my vent temps are 50-55 degrees. Right in the slot on the graph Tore posted.
I'm very skeptical of 39-degree vent temps with ambient at 90....
I live in Houston and rarely need heat, so I disconnected the hoses from the heat exchanger to the chassis flapper boxes, as well. Instead of venting the hoses outwards, I just removed the hoses and used aluminum foil HVAC tape to cover the heat exhanger outlets. Using a standard probe thermometer, my center vent blows 35 - 40 F cooler than the ambient temperature. For example, if it is 95 F outside, I see center vent temperatures between 55 - 60 F.
My father once had an old International Scout. It’s heating system was missing an underhood air duct hose. A family of mice took up residence, the smell was awful. Be sure to cover the openings if you remove the hoses.
Can someone post a pic of which hoses to disconnect? Also, how often are you guys recharging? I had some work done on mine and it stopped blowing cold pretty quick.
08-14-2018, 11:57 PM
How cold is your 964 vent temp and solutions
