Fixing my AC

[JerryC]

I got a lot done today. Started out rough though, Four Seasons evaporator core #5 was messed up with a bent inlet tube.

Napa guy hooked me up with a place called 1-800-Radiators and they sell a "Ranshu" brand evap core with good packaging. It was in near perfect shape. I got the last one here locally.

So what happens when I'm putting the evap cover back on, I bend a few fins on the evap core. I'm hoping it wont leak...

Got every thing AC reconnected, getting the evap cover back on and running the suction line behind the engine were both a real pain.

Put leak detector die in the pag oil before I put oil in the system. I spead it out, 4 in the comp, 2 each in the condenser, accumulator and evap core.

Still have to put the passenger side of the engine compartment back together, battery airbox, assorted hoses and such. I'll do that while pulling a vacuum.

I used the red orifice tube.

Maybe tomorrow I'll get all working.

Heat index hit 111 here today.

 

[wildbill23c]

I have the red orifice tube in mine as well. Purchased 2 of them so I have a spare if I need it in the future. So far so good with mine, yep, definitely want to look into the electric fan when I get the extra money to do so, it'll keep from robbing engine power for sure.

 

[JerryC]

Well it is running again. Seems that I too need a fan clutch.

Refrigerant pressures are too high. I get to the optimum pressures with half the required charge because the fan isn't pulling enough air to cool it down in the condenser. Adding more refrigerant just increases pressure and vent temps.

A quick spritz with the hose dropped the high side ~75psi it was closing in on 350 at one point.

Fan clutches are cheap, $30. Now I have decide if I want to do it or have it done. I've kind of had enough of sweating it out in the garage.

 

[JerryC]

Took a look at the fan itself. It is cracked between every single blade. Couple of them are spreading. It might be that only reason it has not come apart is the weak fan clutch.

Ordered a replacement fan from LMC, $50 including shipping.

Alternator and electric fan upgrade is on the wish list but just can't swing the cash now. The kit Jeff's bronco graveyard sells looks like the one I'd go with, it's got custom brackets to fit to radiator. I'm not a fan (pun unintended) of the ones that you poke plastic rods through the radiator.

 

[wildbill23c]

My AC had the high pressure issue as well with a low charge, seems to have settled down now though. Maybe due to being so hot when being worked on?

I need to get a fan clutch ordered LOL, none of the local parts stores have them in stock, they all have to order them. So I may as well do that myself and save a few bucks. Found one on ebay for $28 and free shipping.

I upgraded the Alternator from the OEM 65amp to a 95amp before I installed my Amateur Radio stuff. The stock alternator had a bad field and figured with installing radio gear the extra juice would be a good thing. Only thing I had to do was swap the pulley from the old alternator to the new one as for some reason they think the Bronco 2's had a serpentine belt? I've never seen one with a serpentine belt.

 

[JerryC]

check the fan, look for hairline cracks on the ring of the fan base. They are hard to see unless you look for them, unless like in my case there are some that are spreading.

 

[wildbill23c]

When it cools down so I can mess with it, and figure out how to get the old clutch off I'll be doing just that. I have another fan already so that's a plus if I need to replace it.

The local Autozone had one available in another town close by so they had it brought over, so I have a new fan clutch.

 

[wildbill23c]

Got the new fan clutch in finally, what a PITA to get the old one to break loose. Once I got the old one out it was pretty easy from there. New fan clutch is working great and the AC is cooling so much better might be able to use it as an ice maker LOL.

 

[IIBRONCOS]

I don't know a lot about electric fans but found this article interesting. I have always had good performance out of a viscous fan clutch. The flex fan on my Bronco II was on it when I bought it and works good.
Scraped this from the web.

Many people also seem to believe that an electric fan will cure their "at speed" overheating problems. Recall that the fan is not even used when at speed, as the natural flow of the of air through the radiator is more then enough (much more then a fan, in fact) to keep the car cool.

Of course, you're not necessarily after better cooling. You've seen those TV commercials or catalogue ads that promise "Up to 17 free HP!" by converting to an electric fan. Well, that's simply not true. There will be a horsepower gain for sure, on the order of 0.5 - 1HP. But remember that the electric power to run the fan must come from somewhere, and that somewhere is the alternator. Electric fans draw quite a lot of current. Most pull surges of 35A or more to start up, then run at 8A-10A. This puts extra load on the alternator. Ever pedaled a bicycle with a generator powered light? If so, then you will know that as the electrical load on a generator/alternator increases, the generator/alternator becomes harder to turn. Suddenly, all that "free" HP you just freed up is once again being used. This time, though, it is being used to turn the alternator. There is also an inefficiency in the whole system. We are converting mechanical energy, to electrical energy, to mechanical again to run the fan. This very inefficient, much less then just driving the fan directly via the mechanical energy of the rotating shaft.

Let's examine the "17 HP!" claim a little further to drive the point home. A little basic math is all that's needed.

One horsepower is 745.69 watts.
Therefore, 17HP = 12,676.89W.
Since W = Voltage * Current, 12,676.89W is 1056 Amps

So in order to do the same work as that stock "17HP" fan, an electric fan would have to continuously draw over 1000 A from the electrical system of the car. Clearly this does not happen. Now I'm sure that somewhere out there is a car or truck with a ridiculously inefficient and so poorly designed stock fan that it actually does rob 17HP from the engine as it turns. But since the RX-7 comes with a well designed freewheeling clutch fan as already explained, the RX-7 is certainly not that car.

There is a dyno chart floating around the RX-7 forums which supposedly show a car gain 10 HP across the board with no other change besides switching to an electric fan. I seriously question the validity of this claim as the 10 HP gain was shown throughout the entire RPM range, all the way to redline. As we all know, the fan clutch should have been disengaged after about 3000 RPM, so it appears that this car was dyno'ed with a stuck fan clutch

 

[JerryC]

Got the new fan clutch in finally, what a PITA to get the old one to break loose. Once I got the old one out it was pretty easy from there. New fan clutch is working great and the AC is cooling so much better might be able to use it as an ice maker LOL.

That's great. I order the fan clutch today, be here tomorrow. Not expecting the fan until Monday or Tuesday. I also got the fan clutch tool set at Advance Auto Parts for $25.

How do the refrigerant pressures look now?

 

[JerryC]

I don't know a lot about electric fans but found this article interesting. I have always had good performance out of a viscous fan clutch. The flex fan on my Bronco II was on it when I bought it and works good.
Scraped this from the web.

There's an Engine Masters youtube video where they dyno different fans. It's pretty eye opening. The clutch fan used the least horsepower, they did not test with an electric fan but said something like by experience they know it uses 1-2 hp. One of the fans took almost 30 HP to drive.

I see a mechanical fan put a load on the engine two ways, drag from pulling air and reciprocating mass. The alternator has to churn an extra 10-15 amps vs the crank spinning the weight of the fan plus the resistance of the air being pulled by the fan.

 

[wildbill23c]

That's great. I order the fan clutch today, be here tomorrow. Not expecting the fan until Monday or Tuesday. I also got the fan clutch tool set at Advance Auto Parts for $25.

How do the refrigerant pressures look now?

I don't know, I haven't hooked up the gauges, its working great so not going to screw with it anymore LOL. Once I fix something I don't go mess with it, especially the AC due to possibly breaking something and having to start over again.

I'll try and check when I get a chance and post up the numbers. I know the R134A will run much higher pressures than the R12 did, which I think is a huge reason why R134A systems don't last as long, higher pressures means more possibilities for leaks.

 

[JerryC]

I have found a couple leaks already, That dye really works. Got one that I have tightened up twice, first time slowed it way down. Have to wait and see about the second time. I guess if it doesn't stop my choices are to take it apart and re-oring it or try stop leak.

Still waiting on the fan...

 

[IIBRONCOS]

I have been using Duracool refrigerant for a number of years. It cools slightly better than R-12 and runs low compressor head pressures. It is a drop in replacement for R-12. It has worked extremely well in all of the systems I have used it on. I have it in a vehicle I put it in over 15 years ago and have not had to work on that system since. And no I do not have any affiliation with the company. Here is a website with information.

http://www.duracool.com/

 

[wildbill23c]

So far my AC seems to be working fine, I just drive such a short distance to and from work that it doesn't have a chance to really cool properly and it doesn't help that 1/2 the 4 mile drive is 25mph and stop and go, so by the time I hit the highway for the other 2 miles it begins to cool then gets shut off LOL. If I jump in and drive a longer distance it works great. Haven't found any leaks and hoping this conversion holds up over time.

 

[JerryC]

I have been using Duracool refrigerant for a number of years. It cools slightly better than R-12 and runs low compressor head pressures. It is a drop in replacement for R-12. It has worked extremely well in all of the systems I have used it on. I have it in a vehicle I put it in over 15 years ago and have not had to work on that system since. And no I do not have any affiliation with the company. Here is a website with information.

http://www.duracool.com/

That looks good, too bad I went the r134 route.

 

[wildbill23c]

Had a chance to go on a 20 mile drive this afternoon. AC worked awesome, outside temp was 98 degrees, had the fan speed on low and was maintaining a very comfortable inside temp...reminds me I need to get a thermometer for inside LOL.

 

[JerryC]

Had a chance to go on a 20 mile drive this afternoon. AC worked awesome, outside temp was 98 degrees, had the fan speed on low and was maintaining a very comfortable inside temp...reminds me I need to get a thermometer for inside LOL.

Excellent ! My fan should be here tomorrow.
I think I have got the leaking connection squared away.
I've been itching to get after it all weekend.

 

[wildbill23c]

Excellent ! My fan should be here tomorrow.
I think I have got the leaking connection squared away.
I've been itching to get after it all weekend.

It has cooled down here a little bit but still in the upper 90's, supposed to heat back up again the next couple days . Sure nice to have working AC. It wasn't cheap, but probably less than 1/2 the cost to have a shop do the work and in the end I learned a few things as well.

 

[JerryC]

It has cooled down here a little bit but still in the upper 90's, supposed to heat back up again the next couple days . Sure nice to have working AC. It wasn't cheap, but probably less than 1/2 the cost to have a shop do the work and in the end I learned a few things as well.

No doubt, I've a grand in my AC now. $225 of it in tools, which is a plus as I like having more tools. I figure it would be more than double that at a shop, labor would be more than a grand by itself. plus the parts would be more expensive.