|
Dave, if you're still snowed in and looking for something to do with the two fans, well you could do the old low speed / hi speed by the old trick of switching them from series to parallel depending on pressures.
|
Thanks, George.
I was thinking about that. I bet I could hook up two relays to do it. Maybe. Take care, Dave |
Just stumbled across some new info.
For quite some time I have known that the 964/993 series has the ability for "after run", ignition off, ~15 minute engine cooldown period using the cabin heater blower. Thread I just followed seems to indicate that the '84-88 Carrera's had the same feature, heater blower control module and heater blower fuses have unswitched power. By default that might also supply power to the footwell blowers. Anyone experience this, footwell blowers running with ignition off, say on an exceedingly HOT day? ~15 minute TDR function inside the cabin heat blower module...?? If this is the case then this would also help to prevent after-run refrigerant over-pressure instances due to rising engine heat post ignition off. Anyone? |
My 85 heater is not the automatic version and has no sensors of any sort at all. It only comes on when the levers are pulled up.
|
Quote:
The top fuse in the engine compartment supplies power to the module, the second one down supplies power to the blower motor. You probably have never had reason to have the after-run function be enabled, or it happened after you walked away from the car. It's easy enough to check the automatic engine cooldown functionality. With the car running remove the connection from the temperature sensor and short it to ground, the cabin heater blower should run even with the heat control levers full DOWN. If not then it is likely that someone has modified your car. |
I have owned it for 20 years and driven it a lot. It has been in more 100+ heat days than I care to remember. I have come home from a day at the track and parked in my nice quiet garage. Shut the car down and unload the car and there is no noise except the tink tink tink of the exhaust system cooling down.
There is no temperature sensor in the heating system. I have been all over that car from ever angle. |
Quote:
Confirmation: http://www.pelicanparts.com/techarticles/911_extra_cooling/911_extra_cooling.htm |
Quote:
|
Quote:
|
Quote:
|
Quote:
|
Quote:
"If you have a pre-84 911 with manual.." otherwise the article makes no sense. I have verified that the blower gets turned on if the engine rises to high while the engine is running, grounded the temperature sensor signal. I have also verified that the module and the blower circuit are powered with the ignition off. '88 Carrera, manual heat. No actual reason for a decisive conclusion either way. But then again, that's how the after-run cooldown blower operation works in the 964 & 993 |
Quote:
|
Unless I read that tech article incorrectly it states "with car stopped" it does not say with motor off. I have my car setup so that I can manually turn on/off the engine blower anytime by moving the heater levers up and kick on the blower motors or footwell blowers at wish. It will definitely allow you to better control engine temp when in hot/heavy traffic. However, I accomplished this by modifying the blower motor/heater relay in the engine compartment. There is post on pelican that explains how to do this. Hope I am not confusing the issue.
|
Quote:
your '87 already had the automatic engine cooldown function. The module has 2 inputs that enable this function. A speedometer input, and the engine oil temperature sensor. My understanding of the operation is that if the car is consistently moving slowly, say stop and go rush hour traffic, and the sensor closes, the cabin heat blower will be powered to help cool the engine down. I have read elsewhere that the thermostatic sensor switch is mount on the oil cooler mounted to the engine case. |
Quote:
you need your vent temps @ about 35-37/38 F quicker in say a block or 2 or maybe A Mile "as fast as possible" and sustained; just above evaporator freezing point to bring the cabin air temp down much faster, 15 minutes is not good, as I am sure you know @ 90-95F your sweating this might not be possible with your pfc eficency you have adding additional fans to your rear condenser is ridiculous and a waste of money (sorry don''t know a better word for this, its not personal) if your rear PFC is SEALED properly to the deck lid letting your engine large fan do the work However INCREASING the air flow into and through your front condenser with a better blower will help you both at idle, stop and go driving, as well as extended driving |
Thanks Reid,
I am just trying to do the best I can with the system I have. I do have an upgraded blower on the front condenser. I have also sealed the rear condenser to the deck lid. I had the 8" fans left over from a project on my 928, so I thought I would try them to supplement the rear condenser air flow at low engine RPM's. It will be easy to run with and without the fans later this Summer and get some actual data on vent temps and a/c pressures. I will report soon. Thans for the suggestions. Dave |
I know you are trying to do the best you can with what you have !
have you ever read through my original thread, there is a wealth of info scattered you have to dig though the crap to find, there is a lot of useful a/c tips and tricks there I have written! Just so I know are you using a thermometer to measure your vent temps? preferably a digital one IR is surface not air and there is a difference |
Quote:
I must not have understood it. Figured it was a follow on to the post 83 discussion. You have manual controls or you have spiffy controls in the post 83. |
Thanks, Reid. I did indeed read your original thread of 2-3 years ago. I have several different thermometers, digital and analog, also IR. I will publish rear condenser inlet/outlet temps with and without electric fans, once the weather gets hotter. I am working with small, incremental changes, not total redesign, as is your case. We shall see.
Dave |
Quote:
|
Quote:
|
Speaking of quick cabin cool down and sub-freezing temperatures....
Provided your system has the "juice" to do so (a ready supply/surplus of liquid refrigerant) you can run sub-freezing temperatures for a goodly period, longer so with the blower speed on high. You just need a good sense for when to begin retarding the thermostat before the onset of condensate freezing. Most modern day heat pump systems in heating mode operate the evaporator well below freezing and then go into "defrost" mode once the evaporator is partially frozen over. |
Quote:
I like digital thermometers for air temperature FYI: YOU NEED TO SET THE SUPERHEAT on your TXV http://forums.pelicanparts.com/uploa...1429755255.jpg I really like the Taylor digital thermometers, they have one model that has on and off switch with NO auto switch timed out You can read the Taylor model number on the bottom one This Taylor Model is their original design and is very accurate for air vents; you used to be able to get this model at grocery stores all over the place but they are now harder to find @ grocery stores and now they mostly carry/sell auto off ones http://forums.pelicanparts.com/uploa...1429755532.jpg http://forums.pelicanparts.com/uploa...1429755605.jpg |
Quote:
|
sorry Dave I don't like being Falsely Slandered
|
Dave I suggest you read and study about "thermal expansion valves and setting super heat"
IF your using one (hint hint) I live in the tropics in south Florida and we use A/C Almost ALL year we rarely use heaters LoL I will monitor your progress, your doing fine with what you have to work with; summers coming for you; here its been 89-90 already later gator |
Quote:
And while you're at it, stop falsely accusing me of "BS" - it makes you look foolish and desperate. |
ronnie your so called I have been educated is a bad joke on YOU
"You have been educated about your error on several occasions and persist in doing so" I am a well educated real Engineer with over 30 years experience and Federally Licensed by the EPA and Universally Certified in all types of Refrigerant Gases and and all type of refrigeration/air conditioning, etc among the many things I do. I DO NOT POST BS LIKE YOU DO, I never post lies! I AM NOT FALSELY ACCUSING YOU !!! YOU CLAIMED EXTENDED DRIVING @ 95 degrees ambient; 27.x degrees you get in your 911 A/C SYSTEM AIR VENT OUT PUT and YOUR EVAPORATOR DOES NOT FREEZE UP The ONLY thing you showed BESIDES YOUR EGO to back up this claim is a picture of an IR Temp Gun aimed into an air vent SEVERAL TIMES WITH NO OTHER PROOF WHATSOEVER! Your A/C Claim IS Thermodynamically IMPOSSIBLE for an automobile on earth, under the Laws of Thermodynamics! Therefore UNTIL YOU "PROPERLY PROVE" YOUR NUMBERS PUBLICLY AND YOUR BS CLAIM I am not going to drop it and will continue to haunt you with fact HERE AND CALL YOU A LIAR and I won't hold my breath! Prove me wrong on anything I say related to early model 911 A/C, don't get petty! PROVE YOUR NUMBERS AND YOUR CLAIM!!! I AM CALLING YOU OUT ON YOUR BS! |
George I had no intention to come here and damage your thread
Ronnie harassed me here first and I am not going to put up with it |
This isn't my thread, I think its Dave's.
|
Quote:
Quote:
Quote:
|
Quote:
Most of us here have advanced degree designations, blah blah, ad nauseam. BFD. Who gives a flip? |
Remember to report abusive posts.
|
Ha!!!
Bob, "The Mighty Pieholio" beneath your user handle = well done (and a big ole' boooo yaaaaa to Eric for that thar Pieholio wordage - too funny) !!!! |
Quote:
Sometimes. |
Quote:
NO engineer , no SANE one anyway, would bring forth a proposal like you have with your "REVERSE THE GASES" idea/(invention?) without at least one of the following. 1. Logical explanation of why you think it works the way you say. 2. Comparative testing results. 3. User contact or testimony. I took the time to make measurements since for me simple logic says this can't work. I took multiple airflow rate measurements across the bottom of the front lid condenser to come up with an average airflow. Same thing with the rear lid condenser with the engine at idle and no "WWESTED" airflow boost. Adjusted the result by the factor of the size of the rear lid condenser vs the front one. You saw the results. Any explanation to offer? |
Super Heat: Total System Superheat & Evaporator Superheat|Testo 550 Functions Part 1
<iframe width="640" height="360" src="https://www.youtube.com/embed/x-ooIJK72jI?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>
REAL A/C EDUCATION! |
Hi guys,
Just a follow up: Today in Chicago it was 94 degrees. I parked the 911 in the sun and let it come up to oil temp. I turned on the a/c and put the interior fan speed on 3 (Hi). The port pressures were 30 PSI low and 160 PSI Hi. This was at 1500 RPM with the a/c temp control on max. The vent temps leveled off at 38 degrees with a digital temp probe. It was just too hot working in the engine compartment to fool around with turning off my fans, but that will be my next experiment. Overall I'm pretty happy with those numbers. Of course at low fan speed the vent temps drop to 33 degrees, but I'd rather have the air flow. Good luck, Dave |
Why 1500 RPM...? Mine idles at 800..
Any chance of testing with/without fans at 800 RPM..? Have you yet settled on a thermostatic switch close/open temperature range to power the fans? |
| All times are GMT -8. The time now is 09:12 AM. |
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website