Gareth Dickens Posted November 23, 2014 Share Posted November 23, 2014 Feeling inspired by the posts I've seen recently for a heater setup, I have started looking into doing my own homebuilt heater/aircon unit. I need the system to be simple, compact and effective. Spares that I have a vailable thus far is: RR P38 blower fans (X2) RRC heater radiators (X2) RR P38 conensor fans (2 sets) 2mm steel plate to fabricate the box. Spares I can get: RRC compressor pump. (It needs to be v-belt driven) RR P38 condensor. RR P38 evaporator. Reciever dryer. Thermal expansion valve. I was thinking of a simple control setup. A slider for hot/cold. A Flap inside the box which directs the air over the heater or evaporator A on/off button for the aircon. A 3 position switch for the blower. Off/Low/High Any suggestions? Could running a RRC compressor with P 38 evaporator condensor cause a mismatch? Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 23, 2014 Share Posted November 23, 2014 They say you can mismatch stuff. I don't know though, the bigger the condenser the easier it can turn gas into liquid? I bet you could have too bigger evaporator when it is compared to the compressor. I can't see how it would damage anything though? Control; Depends how easy you can have a direction flap I guess. I'd have them totally separate with their own fans, sending air to different parts of the cab, but OE builds have the evaporator first and then the air goes through the heating rad. They warm the air back up to get reduced air con temperatures. Fitting the compressor is probably the biggest job, and even if you aren't happy with the air con, you've just fitted a handy tyre inflator Quote Link to comment Share on other sites More sharing options...
Gareth Dickens Posted November 23, 2014 Author Share Posted November 23, 2014 From my limited knowledge of the vapour cycle air conditioning system, I cannot see how the compressor could be damaged by too large condensor or evaporator either. As long as all refrigerant is converted from liquid to gas before reaching the compressor, no damage should occur. The compressor could be running at maximum displacement though. In OEM setups, I think they use a water control valve to regulate the heater radiator temp. I plan not to use one and my engine will permanently be circulating the engine water through the heater radiator. I want to fit a check valves (flap) to the fan exits. One evaprator fan and one condenser fan on is low flow and both evaporator fans and condensor fans on will be high flow. I have looked into using an air con compressor as an air compressor, but the lubrication for the compressor is in the refrigerant. You would have to incorporate a oiler/de-oiler or oil seperator to use it as an air compressor for any extended period. Some older aircon compressors could be used. They had a different lube system. Once I have it properly drawn up I will scan and post it. Untill then all info or cautions are welcomed. Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 23, 2014 Share Posted November 23, 2014 As an aside, Every screw-air separator I've seen is a tank with a filter in it. They don't seem overly complicated. Its the compressed air pressure that forces oil into the intake side of the compressor. It comes from the air tank, goes through a separate oil filter, a cooler and then an orifice. But they run hot which I guess makes water exit the system? They never seem to have milky oil in them? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 23, 2014 Share Posted November 23, 2014 I would definitely run it so you can have AC and heat on at same time -this dries the air considerably and helps HUGELY with de-misting the windscreen.... Quote Link to comment Share on other sites More sharing options...
Gazzar Posted November 24, 2014 Share Posted November 24, 2014 I would definitely run it so you can have AC and heat on at same time -this dries the air considerably and helps HUGELY with de-misting the windscreen.... I don't know how much of an issue that is where GD is based: somewhere south of Southampton, I believe. But on my vapour build (soon - workshop floor in last week) I'm fitting heated screens. Quote Link to comment Share on other sites More sharing options...
Gareth Dickens Posted November 24, 2014 Author Share Posted November 24, 2014 Got al the parts today at the best possible price. (Free) Just need to check if the compressor I got is made for R134A. My buddy has a old R12 compressor lying around. Could use that for tyre inflation? I do have 4 Wabco electric compressors from a mercedes air suspension setup as well. So many choices. Quote Link to comment Share on other sites More sharing options...
Gareth Dickens Posted November 24, 2014 Author Share Posted November 24, 2014 I don't know how much of an issue that is where GD is based: somewhere south of Southampton, I believe. But on my vapour build (soon - workshop floor in last week) I'm fitting heated screens. We do get summer rainstorms that fog the windows up badly. I will start a mockup soon to see what is possible and practical. Quote Link to comment Share on other sites More sharing options...
Gareth Dickens Posted November 25, 2014 Author Share Posted November 25, 2014 Bad news. The RRC aircon compressor I got, runs on R12 gas, so no go on that. I took my Isuzu in for an aircon regas today (summer is here) and spoke to the technician. He told me that some guys run the R12 systems on refrigeration gas (R22) but that it destroys the seals after a few months of running. So I went back to my buddy and picked up a P38 compressor pump. I will have to make a v-belt pulley fit it. Then at least I will have a matched system. I would love heated windows, but they are just not available in South Africa. I managed to get 8 RRC Eyeballs (the round air outlets) and was thinking to use the lower series dash for the air distribution. Quote Link to comment Share on other sites More sharing options...
Ex Member Posted November 25, 2014 Share Posted November 25, 2014 You want to have a heater valve and the air should go through the evaporator first and then the heater matrix. This is not only to allow dehumidification, but to get reasonable temperature control. It will also take up a lot less room than an air flap control system. Look at the area of our fan inlet(s) and make sure the total of your ducting is around that size to prevent restricting the air flow. Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 25, 2014 Share Posted November 25, 2014 I wonder if you will have to make a new pulley, as the clutches don't seem that complicated. Maybe there is a V option on it? Or to look at it the other way, I put an air-con clutch on a small supercharger last year. If everything is centred they look pretty forgiving. The only downer on doubling up cores is the reduced air flow due to back pressure. It might be okay, but I'd dry-assemble it first to make sure. It'll depend on the fin-type vs the fan. Quote Link to comment Share on other sites More sharing options...
supaimpy Posted November 25, 2014 Share Posted November 25, 2014 Bad news. The RRC aircon compressor I got, runs on R12 gas, so no go on that. Actually no, just change the oil to PAG and it will run, dependant on the compressor conditon, s/h parts always a risk. make sure you replace all the 'o' rings to R134a spec and a new drier and it should be ok. Biggest potential issue is the shaft seal, if its dried out it will leak, that why new compressors are charged with OFN too keep them dry and the seals in good condition. Not great using s/h parts for AC builds as you have no idea of whats been in the system such as acids caused by moisture, when its all bolted together I'd do a triple evacuation using Oxygen free nitrogen to get the system as clean as possible. You will need to change the compressor oil anyway as it will be moisture saturated and acid rich from being open to atomosphere If all the parts have come from one vehicle then there will be no mismatch, compressors are generally fixed displacement but does the system your using have a txv or orifice tube? and was the system the compressor was on the same? if the compressor is a variable displacement then that presents more issues. Airflow over the evap coil is vital, if its to low you will risk freezing the coil causing low pressure returning to the compressor with the danger that the gas speed will not be high enough to return the oil to the compressor so you will need an anti frost stat . How do I know , well look at a Snatch Land Rover and wonder who installed the first AC system Quote Link to comment Share on other sites More sharing options...
Gareth Dickens Posted November 27, 2014 Author Share Posted November 27, 2014 So then, first the evaporator then the heater radiator. Heater radiaitor water supply controlled by a heater valve. Does anyone disagree with the above? Should the fans draw the air over the heater and evaporator (suck) and then distribute or should the air be blown over the heater and evaporator? Will the fans survive drawing warm heater air and cold (possibly damp) evaporator air over the motor core? The only downer on doubling up cores is the reduced air flow due to back pressure. It might be okay, but I'd dry-assemble it first to make sure. It'll depend on the fin-type vs the fan. The P38 fans do seem very powerfull. Quote Link to comment Share on other sites More sharing options...
Ex Member Posted November 27, 2014 Share Posted November 27, 2014 You want to blow. The amount of air moved when heating is much higher that way. And most likely the fans are not designed to run hot. Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 27, 2014 Share Posted November 27, 2014 Yes, if it was just air con then you could have a sucking fan, bit a heater rad gives the fan a hard time. Especially if it is running it full amps. Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 27, 2014 Share Posted November 27, 2014 I got distracted there for a bit. It seems to be normal to let stuff run in the hot if it is doing less than full power. At first glance that seems a mad, as the fans are fixed, but there are loads of different fins like louvered and plain. If the fin passes air easily the fan draws less amps and can run in warmer temperatures. That sounds a bit lectury, but it's a handy bit of info if you need it Quote Link to comment Share on other sites More sharing options...
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