ArdWrknTrk Posted May 12, 2023 Share Posted May 12, 2023 Jim - The fan doesn't have that noise by itself, and the noise comes and goes with the A/C compressor's clutch coming in/releasing regardless of fan speed. Interesting... But you hear it coming from the ductwork and not under hood. I have to wonder if the evaporator coil is somehow transmitting the noise. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 12, 2023 Author Share Posted May 12, 2023 Jim - The fan doesn't have that noise by itself, and the noise comes and goes with the A/C compressor's clutch coming in/releasing regardless of fan speed. Interesting... But you hear it coming from the ductwork and not under hood. I have to wonder if the evaporator coil is somehow transmitting the noise. Right - ductwork and not under the hood. Or, maybe "from the dash" would be more correct as I can't really pinpoint where it is coming from. However, when I put my stethoscope on the fittings of the evaporator I don't hear the noise. I do hear a noise that is similar but it doesn't vary by RPM like "the noise" does. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 12, 2023 Share Posted May 12, 2023 Right - ductwork and not under the hood. Or, maybe "from the dash" would be more correct as I can't really pinpoint where it is coming from. However, when I put my stethoscope on the fittings of the evaporator I don't hear the noise. I do hear a noise that is similar but it doesn't vary by RPM like "the noise" does. . Maybe the ghost of is kicking and screaming as you try to evict him from Big Blue? Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 12, 2023 Author Share Posted May 12, 2023 . Maybe the ghost of is kicking and screaming as you try to evict him from Big Blue? LOL! Well, I'd really like to be shed of him so I might be willing to live with the noise if that's what it takes. Heard back from the shop and we agreed to wait until Janey and I get back from our upcoming trip to see the kids before worrying about it. I reported what I'd found, both the pressures as well as lack of finding the source via the stethoscope. And I explained that since I don't have a fan to blow through the radiator and I don't think the clutch on the cooling fan had kicked in that maybe the pressures aren't really high? Anyway, we are on hold. Link to comment Share on other sites More sharing options...
85lebaront2 Posted May 12, 2023 Share Posted May 12, 2023 Bill - The receipt shows "7-4150" which I take to mean they put in a Spectra Premium 7-4150 and Amazon says that's the right one for a 1990 system. And I have a red orifice tube in. The evaporator is from a 1990, and the accumulator is for a 1990. Perhaps I just didn't have enough air flow? I don't think the fan clutch had engaged at that point, but I'm not sure. I don't have a large shop fan for that but the hood was open. Jim - The fan doesn't have that noise by itself, and the noise comes and goes with the A/C compressor's clutch coming in/releasing regardless of fan speed. I have a call into the mechanic and we'll see if he wants me to bring it in. To quote my Spectra Premium parts guy (at the time I was updating Darth) he recommended the 7-4531 which is for the 1994-97 trucks and the 0233091 accumulator. I already had the 1996 evaporator and the 1990 FS10 compressor. I scored a 1996/7 set of lines at Pick-n-Pull VB and I have the largest orifice tube as that is what is recommended for a crew cab. I purged the compressor and replaced the oil with PAG then evacuated and charged with R134a The condenser is described as a multi-pass and is not cleanable if I lose a compressor. I still think what helped the most in Darth, other than using the complete later system is the thermal barrier insulation under the carpet with a double layer over the exhaust pipe area. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 12, 2023 Author Share Posted May 12, 2023 To quote my Spectra Premium parts guy (at the time I was updating Darth) he recommended the 7-4531 which is for the 1994-97 trucks and the 0233091 accumulator. I already had the 1996 evaporator and the 1990 FS10 compressor. I scored a 1996/7 set of lines at Pick-n-Pull VB and I have the largest orifice tube as that is what is recommended for a crew cab. I purged the compressor and replaced the oil with PAG then evacuated and charged with R134a The condenser is described as a multi-pass and is not cleanable if I lose a compressor. I still think what helped the most in Darth, other than using the complete later system is the thermal barrier insulation under the carpet with a double layer over the exhaust pipe area. Yes, the 7-4531 does appear to fit the later trucks. I hope I don't have to do this again, but if I do I might go that way. But it takes different lines? I, too, have insulation under the carpet as well as in the roof, plus on the A/C system. So I'm pretty sure it'll do the job - assuming it has quit leaking. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 12, 2023 Author Share Posted May 12, 2023 Yes, the 7-4531 does appear to fit the later trucks. I hope I don't have to do this again, but if I do I might go that way. But it takes different lines? I, too, have insulation under the carpet as well as in the roof, plus on the A/C system. So I'm pretty sure it'll do the job - assuming it has quit leaking. BRRRR! Just took the truck on a drive to see what the discharge temps are. And I'm chilled! This was in Max mode where it is pulling inside air and the vacuum switch is shutting off any water to the heater. The ambient is 82F with 74% humidity. Here are the readings with the fan speeds: High: 42 to 52, with it staying on 42 for a long time #3: 42 to 52, but less time on 42 #2: 44 to 54, but this was early in the trip #1: 38 to 52, but this was at the end of the trip when the air in the cab was COLD! After a few miles the air blowing on my arms was downright chilly. I think this thing is WORKING! But it still makes a bunch of noise. Link to comment Share on other sites More sharing options...
85lebaront2 Posted May 12, 2023 Share Posted May 12, 2023 BRRRR! Just took the truck on a drive to see what the discharge temps are. And I'm chilled! This was in Max mode where it is pulling inside air and the vacuum switch is shutting off any water to the heater. The ambient is 82F with 74% humidity. Here are the readings with the fan speeds: High: 42 to 52, with it staying on 42 for a long time #3: 42 to 52, but less time on 42 #2: 44 to 54, but this was early in the trip #1: 38 to 52, but this was at the end of the trip when the air in the cab was COLD! After a few miles the air blowing on my arms was downright chilly. I think this thing is WORKING! But it still makes a bunch of noise. Sounds like it is better. Link to comment Share on other sites More sharing options...
AmericanSavage Posted May 13, 2023 Share Posted May 13, 2023 Gary, Off topic: I like that RPM gauge in the center you have. Mine is blank—never had one. Is there a way to add one, and what might that entail? New soft circuit board on the back? And where would someone fine a gauge to fit? Cheers! Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 13, 2023 Author Share Posted May 13, 2023 Sounds like it is better. It cools really well, but it is still noisy. As for tachs, you might want to read the page at Documentation/Electrical/Tachometers. But there's a piece of info that appears to be lacking on that page. If your truck has gauges then the wiring harness is there for a tach. But if you have idiot lights you are basically out of luck. Not only is your truck not wired for the tach, but it doesn't have the needed wiring for the other gauges either and you can't install a cluster with gauges. Assuming you have gauges then you need to check to see if your instrument cluster's printed circuit supports the tach. From our page at Documentation/Electrical/Gauges comes the table below for printed circuits. But it is confusing. So the best thing to do is to pull the cluster out and see what you have. If your printed circuit has copper tabs where the four studs go for the tach then you are in. If not, it'll have to be replaced. And the best way to replace it is to buy a cluster with a tach in it. If you have gauges it'll bolt/plug right in. Link to comment Share on other sites More sharing options...
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