Automotive Air Conditioning Information Forum

Have read in a few sites that to achieve max cabin cooling it is better to acually run the A/C fan speed on a low setting. Can't remember the reasoning I read behind this theory. For the truth what do the experts here say? I know your vent direction button should be set on arrow facing a driver and recirulate. Just maybe it is a under certain circumstance type answer.

Simple answer: Air moves slower across the coil allowing for more time to remove the heat load.

Tim wrote: ↑Tue Apr 30, 2024 7:44 am Simple answer: Air moves slower across the coil allowing for more time to remove the heat load.

1. Yes, the temperature of the air will be lower because of the low speed (see above).

2. The cooling of the person or cabin is determined by how many BTUs are exchanged. So the person will likely be more comfortable at fan speeds that are higher, even if such air has higher temperature. Compare to just a regular fan in a room: if very slow speed, one may not even feel any cooling, and at high speeds one may feel too cold.

So Cusser-My 15 Civics fan speed display shows 1bar (slowest) to I believe 8 bars but will confirm. How many bars would you run fan speed ? Iknow thats a personal preferance. thanks

Run your fan speed where YOU feel comfortable. I find on my '88 Mazda truck, 1998 Frontier, and 2004 Frontier (Arizona) that I use the speed about 3/4 of maximum. Of course with vents directed at occupants.

When it has been parked in daylight, the inside-cabin air is hotter than the outside air, so have in the "outside air" mode for first few minutes, then set to Recirculate/Maximum/Recycle air mode.

In checking my 15 civic the fan speed selector acually goes from 1-7.Going on long trip next week so will try 3 as a fan speed. Not real hot up here yet so thinking it will reach 75F during afternoon Have a middle left vent thermometer set up. If at that temp on sunny day should I read around 50F or should it be colder at that 3 fan speed. Have feeling my one canister of 12a refridgerant wasn't quite enough to hold near the top of the blue good range on my cheap guage.

nanccinut wrote: ↑Fri May 03, 2024 4:32 am Not real hot up here yet so thinking it will reach 75F during afternoon Have a middle left vent thermometer set up. If at that temp on sunny day should I read around 50F or should it be colder at that 3 fan speed.

The local radio show/shop owner/master mechanic here in Phoenix (now retired) used to say that any temperatures below 55F were acceptable, but I think lower. Temperatures will be lower when driving than in neutral due to ram effect of air passing through the condenser, and higher engine/compressor rpm. Electric condenser fans should all be running.

I'm not experienced with 12a refrigerant you're using. You obviously had a leak because you state you already added 1 can, think that leak should be fixed and proper refrigerant added by weight.

Hondas generally have good performing AC, if I remember correctly.

nanccinut wrote: ↑Fri May 03, 2024 4:32 am Have feeling my one canister of 12a refridgerant wasn't quite enough to hold near the top of the blue good range on my cheap guage.

If you're in the United States, why not just use R-134a, which is what your car was originally designed for? Although R-12a reportedly is compatible with the former, it's also hydrocarbon based, quite flammable, and not EPA approved. R-134a is still abundant, relatively inexpensive, and legal to use in the USA.

Lastly, you cannot charge by pressures alone. The refrigerant must be weighed-in using an accurate, purpose-built scale in conjunction with a professional-grade Manifold Gauge Set.