A/C Installation

[grumpin]

Haven't done a good job documenting this (fortunately Dave is) but the A/C is installed and did a highway test run this evening to really check it out.

This is the first Bullnose I've had with a/c so unfamiliar with what is normal and I've only put about 20 minutes in with this one. The two I grew up in did but never paid attention and they were decommissioned too long ago.

The a/c at highways speeds works great. Need to put a thermometer on it but definitely got cold in the supercab.

First, at idle the rpms really take a hit. Drops down to a little over 500. Normally my converted voltmeter stays dead center but a couple times when idling in park or at a stoplight it went significantly to the left. I assume this is all rpm related and alternator output at those speeds as I don't think the a/c clutch pulls much at all. Alt is a 150amp unit on a single v belt.

Second, temps. Huge difference in coolant temp when the a/c is on. Prior to a/c, unless towing up a hill, the gauge stays between O-R when doing any driving at all. Idling in the shop with no air movement and 90 degree weather I've noticed in that past that when it gets to around A the fan clutch kicks in and drops it back down. With the a/c on this evening, even on the highway, it stayed pretty close to the M-A area. The fan clutch always brings it back down but is this much of a temp increase normal?

When we were charging it my neighbor was getting a little concerned with how high the a/c pressure was getting before the fan clutch kicked in. Once it kicked in, everything leveled out but I don't like the idea of there being any risk at all if running the a/c at idle. Should I change something to make the fan clutch kick in sooner? It's a new one replaced during the rebuild so 1500 miles on it.

The aluminum radiator came with a shroud with 2 electric fans built into it but most I've read says to stay with the mechanical fan.

With the condenser in front of the radiator, it has to be warmer the way I see it.

I haven’t had my fan kick in while servicing it. But we’re most likely not as warm as your area.

It comes on in traffic at a stop and fades out once I’m going. It sounds all right to me. Id keep an eye on it and see if it stays consistent.

[Gary Lewis]

Haven't done a good job documenting this (fortunately Dave is) but the A/C is installed and did a highway test run this evening to really check it out.

This is the first Bullnose I've had with a/c so unfamiliar with what is normal and I've only put about 20 minutes in with this one. The two I grew up in did but never paid attention and they were decommissioned too long ago.

The a/c at highways speeds works great. Need to put a thermometer on it but definitely got cold in the supercab.

First, at idle the rpms really take a hit. Drops down to a little over 500. Normally my converted voltmeter stays dead center but a couple times when idling in park or at a stoplight it went significantly to the left. I assume this is all rpm related and alternator output at those speeds as I don't think the a/c clutch pulls much at all. Alt is a 150amp unit on a single v belt.

Second, temps. Huge difference in coolant temp when the a/c is on. Prior to a/c, unless towing up a hill, the gauge stays between O-R when doing any driving at all. Idling in the shop with no air movement and 90 degree weather I've noticed in that past that when it gets to around A the fan clutch kicks in and drops it back down. With the a/c on this evening, even on the highway, it stayed pretty close to the M-A area. The fan clutch always brings it back down but is this much of a temp increase normal?

When we were charging it my neighbor was getting a little concerned with how high the a/c pressure was getting before the fan clutch kicked in. Once it kicked in, everything leveled out but I don't like the idea of there being any risk at all if running the a/c at idle. Should I change something to make the fan clutch kick in sooner? It's a new one replaced during the rebuild so 1500 miles on it.

The aluminum radiator came with a shroud with 2 electric fans built into it but most I've read says to stay with the mechanical fan.

It sounds as if your clutch isn't coming in soon enough. Can you take a reading with and IR thermometer and find out where it is coming in?

Is there room to get the electric fans and shroud in there? Bill didn't think so on Darth, but maybe yours would fit? If it was me I think I'd try that and see if it helps - assuming you have all the bits needed. That would give you the ability to tune the on/off temps to where you want them. And you could have a light that tells you when they are on.

As for the idle speed, Big Blue's idle speed didn't use to change enough to even notice with his A/C. And that was when the engine was dropping at least one cylinder, if not two, at idle. So I'm surprised that your idle speed is dropping that much.

[Gary Lewis]

It sounds as if your clutch isn't coming in soon enough. Can you take a reading with and IR thermometer and find out where it is coming in?

Is there room to get the electric fans and shroud in there? Bill didn't think so on Darth, but maybe yours would fit? If it was me I think I'd try that and see if it helps - assuming you have all the bits needed. That would give you the ability to tune the on/off temps to where you want them. And you could have a light that tells you when they are on.

As for the idle speed, Big Blue's idle speed didn't use to change enough to even notice with his A/C. And that was when the engine was dropping at least one cylinder, if not two, at idle. So I'm surprised that your idle speed is dropping that much.

Oh, and I forgot the coolant temp. I couldn't see any change in it when the A/C was on either. And I have an aftermarket gauge.

[old55pete]

Haven't done a good job documenting this (fortunately Dave is) but the A/C is installed and did a highway test run this evening to really check it out.

This is the first Bullnose I've had with a/c so unfamiliar with what is normal and I've only put about 20 minutes in with this one. The two I grew up in did but never paid attention and they were decommissioned too long ago.

The a/c at highways speeds works great. Need to put a thermometer on it but definitely got cold in the supercab.

First, at idle the rpms really take a hit. Drops down to a little over 500. Normally my converted voltmeter stays dead center but a couple times when idling in park or at a stoplight it went significantly to the left. I assume this is all rpm related and alternator output at those speeds as I don't think the a/c clutch pulls much at all. Alt is a 150amp unit on a single v belt.

Second, temps. Huge difference in coolant temp when the a/c is on. Prior to a/c, unless towing up a hill, the gauge stays between O-R when doing any driving at all. Idling in the shop with no air movement and 90 degree weather I've noticed in that past that when it gets to around A the fan clutch kicks in and drops it back down. With the a/c on this evening, even on the highway, it stayed pretty close to the M-A area. The fan clutch always brings it back down but is this much of a temp increase normal?

When we were charging it my neighbor was getting a little concerned with how high the a/c pressure was getting before the fan clutch kicked in. Once it kicked in, everything leveled out but I don't like the idea of there being any risk at all if running the a/c at idle. Should I change something to make the fan clutch kick in sooner? It's a new one replaced during the rebuild so 1500 miles on it.

The aluminum radiator came with a shroud with 2 electric fans built into it but most I've read says to stay with the mechanical fan.

I know this may be a stupid question but here goes, Are you sure that you have the correct fan clutch? There are two listed for your pickup, one with out A/C, E3TZ 8A616-L and one with A/C, E3TZ 8A616-P. Having the wrong fan clutch could be the difference in the engine temps and the higher pressures you are seeing. Same thing if you have the wrong fan shroud and fan.

I also saw that you said that the idle was down to 500 rpm with the A/C on. Correct me if I am wrong, shouldent there be an idle kicker on the carb that is supposed to kick up the idle when the A/C is on?

[kramttocs]

I know this may be a stupid question but here goes, Are you sure that you have the correct fan clutch? There are two listed for your pickup, one with out A/C, E3TZ 8A616-L and one with A/C, E3TZ 8A616-P. Having the wrong fan clutch could be the difference in the engine temps and the higher pressures you are seeing. Same thing if you have the wrong fan shroud and fan.

I also saw that you said that the idle was down to 500 rpm with the A/C on. Correct me if I am wrong, shouldent there be an idle kicker on the carb that is supposed to kick up the idle when the A/C is on?

Thanks all. I'll do some more testing this afternoon.

I bought the Hayden 2799. I believe it's correct with a/c but was wondering the same yesterday.

[old55pete]

Thanks all. I'll do some more testing this afternoon.

I bought the Hayden 2799. I believe it's correct with a/c but was wondering the same yesterday.

A little tidbit I found while researching your fan clutch.https://youtu.be/UHWxqRWt9Kw

[kramttocs]

A little tidbit I found while researching your fan clutch.https://youtu.be/UHWxqRWt9Kw

Good find Steve. Never knew they could be adjusted.

Just ran out and did some testing after church. Slightly different behavior than I saw yesterday and curious to see what you guys think.

Builder said to use a 195 thermostat but when I sent all the details to Scott for the recurved distributor he said to use a 180 so I've only ever ran the engine with that. 4 row aluminum (Champion style) radiator.

This test was inside my metal, uninsulated shop building with no fans running. Outdoor temp is 88 degrees and 60% humidity so it was pretty warm in there.

Started truck. Let it run for just a couple minutes. RPM at 750-780 idle. Park (auto trans) dropped it to 650.

I was taking measurements at the thermostat housing and on the fan clutch itself once the temp got up to O on the gauge.

Housing/clutch/gauge/fan

A/C off

170/140/O-R/off

177/145/R/off

180/155/M/off

185/159/M-A/off

194/160/A/on (stayed on until I shut the engine off)

171/156/M/on

165/148/R/on

164/149/O-R/on

RPM is now at 850

A/C on max and fan on low

RPM drops to 760

No change in voltmeter

Gauge climbed back to R-M and stayed for a few minutes until I shut the engine off

-----

Anything look alarming with those temps/numbers?

My 400 in the 80 with the numerical gauges hovers between 190 and 210 (when towing).

[Rusty_S85]

I know this may be a stupid question but here goes, Are you sure that you have the correct fan clutch? There are two listed for your pickup, one with out A/C, E3TZ 8A616-L and one with A/C, E3TZ 8A616-P. Having the wrong fan clutch could be the difference in the engine temps and the higher pressures you are seeing. Same thing if you have the wrong fan shroud and fan.

I also saw that you said that the idle was down to 500 rpm with the A/C on. Correct me if I am wrong, shouldent there be an idle kicker on the carb that is supposed to kick up the idle when the A/C is on?

There should be a kicker and it should idle the engine up. Spec on my '82 which doesnt have the kicker as it is dealer A/C, its 550 rpm idle with ac off and with ac on its 675 rpm.

Its a big thing I plan on for my fuel injection conversion to go into the software and change the A/C kicker into an A/C idle stepper so I can have a 550 rpm idle if my cam will allow it and have a 675 rpm idle with the A/C on.

On the fans I believe one of those clutches is a rpm based clutch and the other is a thermal clutch. I know the thermal clutches you find now at the part stores are HD variants and I hate them cause they lock up way too easy and make your truck/van sound like an airplane taking off. There is also a listing for a flex fan for A/C equipped vehicles as well, the standard non A/C flex fan is a 5 bladed flex fan while the A/C flex fan is a 7 bladed flex fan that is like 1/2" larger diameter than the 5 bladed. This is the route I personally have gone to try and correct my A/C setup on my dealer A/C truck. I get 58* ambient temp out of my dash on a 100* day all day long at idle but I feel I could get better performance with the proper air flow and a proper thermostat switch.

[old55pete]

Good find Steve. Never knew they could be adjusted.

Just ran out and did some testing after church. Slightly different behavior than I saw yesterday and curious to see what you guys think.

Builder said to use a 195 thermostat but when I sent all the details to Scott for the recurved distributor he said to use a 180 so I've only ever ran the engine with that. 4 row aluminum (Champion style) radiator.

This test was inside my metal, uninsulated shop building with no fans running. Outdoor temp is 88 degrees and 60% humidity so it was pretty warm in there.

Started truck. Let it run for just a couple minutes. RPM at 750-780 idle. Park (auto trans) dropped it to 650.

I was taking measurements at the thermostat housing and on the fan clutch itself once the temp got up to O on the gauge.

Housing/clutch/gauge/fan

A/C off

170/140/O-R/off

177/145/R/off

180/155/M/off

185/159/M-A/off

194/160/A/on (stayed on until I shut the engine off)

171/156/M/on

165/148/R/on

164/149/O-R/on

RPM is now at 850

A/C on max and fan on low

RPM drops to 760

No change in voltmeter

Gauge climbed back to R-M and stayed for a few minutes until I shut the engine off

-----

Anything look alarming with those temps/numbers?

My 400 in the 80 with the numerical gauges hovers between 190 and 210 (when towing).

Nope, all of these readings look pretty N O R M A L to me. Still cant wrap my head around why someone would tell you to use a lower temp thermostat in a low compression engine, but I am not going to go there.

[Rusty_S85]

Nope, all of these readings look pretty N O R M A L to me. Still cant wrap my head around why someone would tell you to use a lower temp thermostat in a low compression engine, but I am not going to go there.

lol Im still trying to decide what thermostat to run in my 306. Should be around 9.5:1 compression maybe as high as 9.75:1 but I initially planned on running a NOS OE 195 thermostat but I have many telling me that even with my fuel injection to stick to the 180 I currently have in my smog engine.