Dual Alternators for A/C Removal, newbie

[joexsmoot]

Good morning everyone! I'm joe, new to the forum. To give a super quick backstory, I bought a 87 Minnie Winnie for $500 about a year ago, it was stripped and a leaky mess. 1 year later, me and my girlfriend updated the whole thing. Took it on one or two trips, engine smoked a lot.

Fast forward, i'm pulling the 460 8 cyl 7.5l EFI out, and replacing with one with lower mileage. The A/C did not work, and it is the old style refrigerant which is hard to come by and expensive, especially if I don't even know why it didn't work. However our 110v roof top unit works amazingly, and i'd like to capitalize on that.

Is it possible and realistic to remove the A/C compressor and install an additional alternator in it's place? I would run the 2nd alternator's lead (with external voltage regulator) directly to a fuse block which connects to my house battery bank and the DC to AC inverter

Ideally, it'd go something like this:


This would be something that would benefit me by: saving me to upgrade the A/C system to the current refrigerant, be a lot more cost effective (alternator is $100 autozone, wiring and fuse roughly $80, no frills regulator $30-50) VS starting off with a $350 compressor (autozone) let alone whatever else needs to be replaced (sensors, tubing, condenser, cooler, blower assembly are all 35+ years old, plus refrigerant etc). When the DC to AC inverter isn't drawing more then what the 2nd alternator is supplying it acts as a charging unit for my batteries, which saves me $100-300 just for that unit alone.

I don't use the unit dry very often, it's usually hooked up to some form of campsite power. I figure this method would be best for my short and sporadic uses. It benefits me cost wise, I don't ever plan on selling, and I don't foresee a power issue seeing the house batteries / appliances are a completely isolated charging system.

What do you all think?? Let me know, feel free to give me any ideas or issues you forsee in the future!




THANKS EVERYONE!!!

[ron_dittmer]

joexsmoot,

About your chassis a/c system, if it proves to be hopeless, I would consider doing what I had done with our old 1991 Mercury Capri. It's a/c system was not practical to repair because there were too many things wrong with it. So I decided to uninstall the system, just as if the car had none when new. Removing everything really opened up the engine bay and removing the evaporator under the dash board got rid of the fowl odor coming from there from all the debris that collected in that area. As a result, air flow through the ventilation system improved, but also engine bay ventilation was much improved without the condensor. I found the results very satisfying. Assuming the a/c system on your 1987 chassis was optional, theoretically all you need to do is buy the "V" belt for the non-a/c model like I did with our Capri.

Regarding a second alternator, I would not unnecessarily complicate your electrical system and your engine bay. If you require more amperage from your alternator, I would replace it with a 140 amp one from JC Whitney for $220 which will supply more amperage than the ones Ford puts in brand new 2017s.

If I were in your shoes, I would think "Simplicity" and "Affordability".

I know you are also looking into an on-board 110V generator. Given your destinations with electricity, it sounds like you really don't need a generator except when driving for the purposes of running the roof a/c. Given the age and weight of your old rig, I would consider avoiding a generator for the sake of the weight. Of coarse this means you have no a/c of either kind when driving. But to be honest, I highly question if the roof a/c will provide enough front cab comfort anyway.

Our first motor home HERE was on a Toyota chassis. It had no a/c of either kind, and no power steering either. We ordered it that way for simplicity & reliability. We lived without a/c like that for 24 years. It wasn't until we were knocking on 50 years of age when we wanted to increase our comfort in many different areas of RVing including having both kinds of a/c.

With such an old rig like yours, I wouldn't want to invest more than necessary. Figure out what is the least you can live with and head into that direction, and then enjoy.

Ron

[joexsmoot]

Wow thanks for the continuing answers everyone.

Rick Jay - I've got a set of gauges, just never worked with the r12 before. Its pretty intact from what I can tell, I removed the cooler and condenser in preperation to remove the engine. I think i'll test out the system, and as long as no leaks or hard to find leaks i'll do the conversion like birdfreak had mentioned. If there are issues, I guess it'll be up to how many issues I run into. I found a few 4000w generators online used for a couple hundred, that I could make work (safely). I really gotta do some more researching and price out my options! hah

Harvey - Anything 1996 and older uses r12, so you do apply. I have read now that some vehicles' compressors are able to accept the r134a with little to no issues. Some cant handle the high pressures generated by r134a and kick the bucket. Its worth a shot if its not going to cost much to try. If I really don't have to replace anything other than o rings and the high / low service ports, that is the cheapest. I'll go to autozone after work today and check it out.

DownTheAvenue - Is there really?? Wow. thats great to know! I wonder how much they cost haha. Another thing to look into. That lessens the stress on the battery bank / inverter while the rig is running.

CharlesinGA - Yes i'm EFI. No 4 barrel carb for me. 1987 e350 1 ton with 7.5 EFI's make up on 3% of all sold in 87' (according to autozone). lucky me. Finding parts can sometimes be difficult, though 88 and 89 are pretty much identical. 91' is when i find part numbers don't interchange. I did a compression test on all 8 cylinders, sadly there was only a 15 PSI variance between all 8. What I did find was finally after draining the radiator, I found large sludgy/oily globs in the bottom. While the rig smoked it never smelled of coolant, the coolant was always bright green, and the oil was always brown/black but not chocolate milk looking. I recently got a knocking noise when starting the motor, suggesting internals, oil pump/pressure/delivery/ or the transmission flexplate (from what ive found on forums) so instead of trying to take it apart inside the RV it was easier to pick up a running motor($380) with similar mileage(53,000), change out everything on a bench and swap that one in. The current motor i'll put on CL. Ive heard they are true workhorses and will last if they are taken care of properly. I considered at one point throwing in the 7.3 or 6.9 IDI but that seems like more trouble then its worth. For 1 MPG, for me not worth the cost / labor. Maybe if I fulltimed but to each their own.

[CharlesinGA]

Are you sure the engine is fuel injection? (throttle body injection actually)? I seem to recall that mid '88 CHASSIS year is where the change over occurred.

Have you done a compression check? the oil consumption could be something as simple as needing new valve seals. I would expect the old ones to be hard and have cracked and fallen off by now. The TBI 460 is a great engine.

Charles

[DownTheAvenue]

There are 120 volt alternators available and are now an option on some Roadtrek Class B motorhomes. It is very doable!

[Bird_Freak]

joexsmoot wrote:
Bird - Would you mind to point me in the right direction if you have any websites? Any I've found say to replace pretty much everything, or r12 for outrageous prices.

Thanks! I'll start looking some more then i guess.

If only you were closer to NJ. I'd bring it to you!

Go to local parts store and tell them you want a conversion kit to R134, Cheap, This will be the ports you need to convert lines to take 134 gauges. You will need a flush kit and may have to break lines loose and replace o rings with the green ones due to age. You also need to change the dryer and oil in compressor if you don't change compressor. Check Autozone or O riellys. They can put you on track for cost to change. Also check Rockauto.com for best prices.

[Harvey51]

Our 1992 GM van is 5 years newer so maybe not the same deal. Anyway, the A/C failed three years ago. My retired mechanic and refrigeration tech friend told me to buy two cans of upgrade refrigerant at the auto supply store, about $40 I think. He pumped out whatever was left in the system and added these two cans of refrigerant. Took about an hour. Still working fine.

[Rick_Jay]

joeexsmoot,

Welcome to the Forums! 🙂

If the A/C system is still in tact, you don't have to put refrigerant in it to see if it's leaking. Just pull a vacuum on it and see if it'll hold it. You can have somebody do it for you, or if you are planning on doing the work yourself, it's worth the investment. There are probably others, maybe even cheaper and no endorsements for this brand or retailer: Harbor Freight Vacuum Pump

A set of gauges is about $60 bucks for R-134 systems, which is what you'll probably end up converting it to. Unless, of course, it doesn't leak.

If you know it leaks, you can just shoot a bit of refrigerant with a dye in the oil to find the leak with a UV light. Again, a bit more money, but if you do it yourself, fairly reasonable compared to having someone do the work for you.

However, if the compressor, condensor, evaporator or hoses have been damaged, the dollars can add up fast. In a rig that old, I'd be tempted to just rig up a decent generator and run the roof air.

I would be cautious about putting too much money into it.

And yes, when shops hear "motorhome", the rates often raise. Sometimes it might be justifiable, but at least in my experience, testing/charging the A/C system isn't any harder for me to do on my motorhome than on our minivan & SUV or any car I've had previously.

Good Luck,

~Rick

[joexsmoot]

Old Wizard - thanks! yes thats true. 100a wouldnt get me very far, ideally i'd need 200 - 300a which they do sell, but can be just as expensive as well, getting the A/C fixed haha. Good call.

Sam - My understanding was if i replace the compressor, and the dryer, yes I'd be able to use r134a but that comes at an added cost. compressors are $300+ alone, but in the long run it may honestly be worth it from what you guys have shown me. I really appreciate all the help and advice. A lot I honestly didn't take into consideration or didn't know.

Oh yes I agree, internet info can go both ways good and bad. As far as quotes go, I'm thinking I just won't mention the motor home part of it. I was getting quoted $140 an hour for motor home diagnostic charges, they said they charge differently then your usual car and truck. I thought that's total BS but then again all I can do is look elsewhere. Anytime I say those words I see $$ in their eyes. I'll call and check out a few more shops and see.

[Sam_Spade]

joexsmoot wrote:
I could replace it but i'm trying to avoid that because of the high costs the refrigerant.

I think you have a major misunderstanding here.

If you replace the major components of the system, IE compressor and dryer you will NOT use "old type" refrigerant. It won't be quite as efficient as it originally was but should be adequate.

I think the dryer is the only part that must be replaced and the compressor can be re-used too if it is in good enough condition.

And finally, I KNOW that some people are obsessed with the Internet but some things are best done in person. Honestly.
Visit an A/C shop or two in your area. Ask what they would charge you to diagnose it. I think $300 is outrageous......unless they charge $150 per hour for labor. It should take them no more than 2 hours; more like one is my guess.

[joexsmoot]

Thanks turbojimmy. I'll look into it a bit more, when i originally looked it was all seeming pretty pricey. Changing the drier and adding oil isnt too bad. and a used or reman compressor would be cheap enough to try out.

I'll keep my eyes open for generators on CL. I have seen onan generators for a 150-250 every once in a while. we will have to see.

Thanks everyone for their input. all good things to look into

[theoldwizard1]

Bird Freak wrote:
Some one is ripping you off! R134 conversion kits are cheap and there are r12 compatible refrigerants available. Been doing this for years.

R12 IS available, but only until about 2020 (?)

Run what ya got !

[theoldwizard1]

Sam Spade wrote:

joexsmoot wrote:

Is it possible and realistic to remove the A/C compressor and install an additional alternator in it's place?

What do you all think?? Let me know, feel free to give me any ideas or issues you forsee in the future!

Possible, probably.
Realistic, certainly NOT.

Well, I'll disagree. It will be "challenging".

First, you are going to need a pretty good sized "house battery", maybe 4 - 6V deep discharge batteries, like Trojan T105s.

Second, mounting a second alternator in the exact same spot as the original A/C compressor likely will take some custom brackets.

Third, an external, adjustable voltage regulation is a good idea. You will need a permanent volt meter to monitor it.

Fourth, you are still going to need a good high power battery charger to recharge the house bank.

Even with a 100A alternator, you are marginal for making enough power to maintain the batteries, run the inverter and run the A/C.

[turbojimmy]

joexsmoot wrote:
Bird - Would you mind to point me in the right direction if you have any websites? Any I've found say to replace pretty much everything, or r12 for outrageous prices.

Thanks! I'll start looking some more then i guess.

If only you were closer to NJ. I'd bring it to you!

Google "R12 to R134a conversion" - you'll get a ton of hits. So long as the system hasn't been sitting open for a long period of time you should be able to convert it fairly inexpensively. You need to replace the accumulator/drier since the desiccant in it will have absorbed the oil from the R12 system which is not compatible with the PAG oil in R134a systems. If the compressor is bad, replace that too and add PAG oil. If it's good, drain the oil out of it and replace with PAG oil. Charge the system with R134a and adjust the low-side pressure up a bit (R134a requires a bit higher pressure). You can find step-by-step instructions that are model-specific by searching online. This will be by far your least expensive route if you decide the chassis A/C is the way to go. That being said, my experience has been that dash A/C in motorhomes is marginal at best. There is too much work for it to do. You have a better shot in a Class C since there's less glass and it's easier to close off the cab.

I would spend the money on a generator to power your roof unit. Forget the inverter. To build something that will actually work reliably will cost a lot more money than a small generator.

[joexsmoot]

Bird - Would you mind to point me in the right direction if you have any websites? Any I've found say to replace pretty much everything, or r12 for outrageous prices.

Thanks! I'll start looking some more then i guess.

If only you were closer to NJ. I'd bring it to you!