My air has been only moderately cool so I checked Low pressure with gauge it's showing 45PSI, which I believe is too high and might be causing the problem. Any suggestions on who I'd take to reduce pressure? Could clogged lines cause this as well? Thanks.
How to reduce AC system pressure?
- Thread starter LCMemphis
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Overall high pressure is typically an indication of inadequate airflow thru the condenser. Does it cool fine while on the highway, and gets warm when you stop at a light? Of so, I would start looking at the engine fan viscous coupling (aka clutch).
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thank for the suggestion. I did have freon added about a month ago so could it be they simply added too much?
bloc
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“Does it cool fine while on the highway, and gets warm when you stop at a light?”
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Yes, performs fine on highway..it's around town that it gets spotty and seems to cycle warmer air. Volume of airflow isn't all that great either.
bloc
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@marques post has good info to chase then. If you don’t have enough airflow over the condenser core the low side pressure will read high even if the system is not over filled.
Yes it’s possible they put too much in, but that wouldn’t lead to poor cooling at low speeds and adequate at high.
have 91 3FE, added R-12 replacement Freon to about 48 psi. the local AC guy says you can't do it by pressure has to be by weight. Anyone know the required weight of coolant? I got the Replacement R134a on eBay with the gauge and adaptor fitting
With a running hot engine, if you pop the hood, the fan should be pulling plenty of hot air thru the radiator into the engine bay. And if you tried to stop it (the engine fan), with a roll of paper towels or something else that's not your hand and unlikely to break the fan blades, you should encounter plenty of resistance and it should just continue turning. If the airflow is kind of weak, and you can actually stop the engine fan, you most likely need a new fan clutch.
Or, with the engine off, you can compare how hard it is to turn over the engine fan by hand first thing in the morning (cold engine), and compare that with how much harder it is to turn when everything is hot. It should turn relatively easily when cold, and you should feel significantly more resistance when hot.
I've had this problem on other cars that only have an electric radiator fan. When the fan died, there A/C was definitely not cooling very well when stopped, but fine while out on the highway. And no, the coolant temperature gauge wasn't moving from the middle. Many of today's cars artificially keep the temperature needle right in the middle even as the coolant temp. varies. and only shows cold or hot when it is way cold or way hot.
Or, with the engine off, you can compare how hard it is to turn over the engine fan by hand first thing in the morning (cold engine), and compare that with how much harder it is to turn when everything is hot. It should turn relatively easily when cold, and you should feel significantly more resistance when hot.
I've had this problem on other cars that only have an electric radiator fan. When the fan died, there A/C was definitely not cooling very well when stopped, but fine while out on the highway. And no, the coolant temperature gauge wasn't moving from the middle. Many of today's cars artificially keep the temperature needle right in the middle even as the coolant temp. varies. and only shows cold or hot when it is way cold or way hot.
bloc
SILVER Star
Engine-off rotating the fan isn’t that simple. When the engine is cold all of the oil drains to the bottom, putting it in the outer diameter of the friction plates and causing drag. This is why the fan roars for a while on a cold start, until the fluid is pumped back into its storage reservoir.
