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Hugh R's Avatar
 
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Anyone here ever run their A/C without the deck lid condensor?

I think it may act more like and evaporator than a condensor, especially when you're in bumper-to-bumper traffic. I have a L/R qtr. panel, a small (18"square) underbelly, and the front condensor. Any thoughts?
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Old 07-30-2008, 07:46 PM
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Bump, any thoughts on this. I have a vacuum pump for the weekend only.
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Old 08-01-2008, 06:45 PM
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the compressor will lock up undoubtedly.
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Old 08-01-2008, 06:47 PM
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so if you're over evaporated or under condensed, the compressor will lock?
Old 08-01-2008, 06:52 PM
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JW, can you elaborate?
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Old 08-01-2008, 07:05 PM
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Your compressor will slug only if you are getting liquid in the suction side. If your txv is allowing too much liquid to pass (your superheat is not set to design) you will have more liquid entering the evaporator than can effectively absorb the heat and will allow unevaporated liquid in the suction line to the compressor. This is essentially a the same as hydrolock in a cylinder, trying to compress a liquid.
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Old 08-01-2008, 07:06 PM
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If you remove the condenser you will remove the system's ability to convert the hot, high pressure gas from the compressor to a cooler liquid. Condenser= changing hot gas to cool liquid=condensing. You will then feed gas (instead of liquid) through the txv and into the evaporator. This defeats the design. You need cold liquid in the evaporator to absorb the heat from the air passing through the coil that in turn is blown out of the a/c vents. If you remove the systems ability to condense the gas into a liquid you will reduce it's ability to create cool air.
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Old 08-01-2008, 07:12 PM
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I understand the purpose of the condenser. What I'm wondering about is how much heat soaking the condenser above the engine gets and am I getting a net heat gain to the system from the engine heat, or a net cooling in the car from the fact that it is a condenser. I think Porsche put the deck lid condenser there because it was the only place that made sense (i.e., the engine fan pulled cooling air in for the condenser and the engine.
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Old 08-01-2008, 07:15 PM
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The condenser will not act as an evaporator simply because to evaporate you must start with a liquid in the coil. The condenser is filled with hot, high pressure gas directly from the compressor. You cannot evaporate a something that is already evaporated (gas). The condenser changes the gas to liquid which is converted back to gas by the evaporator. Worse case the condenser will never actually "condense the gas".
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Old 08-01-2008, 07:21 PM
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Ok, now that makes sense! Thanks Mark.
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Old 08-01-2008, 07:25 PM
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Quote:
Originally Posted by Hugh R View Post
I understand the purpose of the condenser. What I'm wondering about is how much heat soaking the condenser above the engine gets and am I getting a net heat gain to the system from the engine heat, or a net cooling in the car
There's no heat soaking the condensor, at least when the engine is running. Air is being sucked through the condensor, through the fan. Even at idle, the amount of air being drawn through it is a lot, running on the road it is substantial.
Old 08-01-2008, 07:26 PM
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There's no heat soaking the condensor, at least when the engine is running. Air is being sucked through the condensor, through the fan. Even at idle, the amount of air being drawn through it is a lot, running on the road it is substantial.
True.
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Old 08-01-2008, 07:31 PM
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That rear condenser has air pulled thru it from top side by the engine fan at idle and by the car aerodynamics when underway. Lots of air! Driving or idling.

Probably 10 times more air thru that condenser than goes thru some little fender well condenser or underbelly.

Probably 100 times more airflow than those extra condensers at stop and go....unless you got the little computer fan on the wheel well...then its probably 50 times more flow.

So remove that rear condenser and you can test whether your high pressure cutoff switch will work and if it doesn't then when the high side hits 500psi or more------ kaaaaabbbbbooooom!!!
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Old 08-02-2008, 06:01 AM
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And remember, there was NO high or low cutoff switch on the York compressor. Don't remember what year they started.
Old 08-02-2008, 06:06 AM
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So remove that rear condenser and you can test whether your high pressure cutoff switch will work and if it doesn't then when the high side hits 500psi or more------ kaaaaabbbbbooooom!!!
True that. If you aren't condensing (removing heat) you stand a very good chance of discharge pressure running away.
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Old 08-02-2008, 07:19 AM
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so, if you have a rear condenser, and want to move it due to a tail change (i'm thinking about 964 motorized) nothing will be as efficient as the rear? I was thinking underbelly...but do I need an underbelly AND another one?
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Old 08-02-2008, 01:46 PM
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Underbelly not as efficient - no big airflow like the rear decklid.
Old 08-02-2008, 04:32 PM
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idle the engine and run the A/C with the engine lid up for a while and see if the compressor starts to lock up. pretty much the same as if it wasn't there.
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Old 08-02-2008, 04:55 PM
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Thanks for the education!
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Old 08-02-2008, 04:59 PM
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