W124 Aux fan upgrade -- Single to Dual - Page 2 - PeachParts Mercedes-Benz Forum

Zulfiqar · #16 06-22-2012, 10:22 AM

A good condenser and radiator fin cleaning really helps. In my late 124 (R134 from factory), I could see light being passed through fins of both heat exchangers but I could also see fluff stuck to the condenser fins.

I cleaned it out with regular home depot evaporator coil cleaner after removing the front fans and the radiator too, It really helped in A/C performance.

Air&Road · #17 06-22-2012, 10:49 AM

Add a combing to what Zulfigar recommended. You can get a comb from the a/c supply houses that will let you straighten the fins more quickly than any other way I've found. When you take the condensor out for any reason, you should always straighten up the radiator fins as well.

Hope this helps

jcyuhn · #18 06-23-2012, 05:21 PM

Quote:

Originally Posted by ps2cho

Today from engine cold 104F, freeway vent temps were 50F after 15mile drive...

BUT 2hrs later still 104F ambient....15mile drive back home, Engine HOT, freeway vent temps were 60F, and once at the stop light, it was at 70F from vents.

That is with Aux fan running on high.

As you can see, the issue seems to be that the condenser cannot shed the heat once its warm! I see the only way to get decent vent temps is doing a full upgrade along with back converting to r12.

Hitman you said the fuel cooler cannot be used? Did they remove it from the later models?

OK, I can see where those vent temps aren't going to cut it - BTDT. You should be getting better performance. I just checked the NOAA website for Phoenix, and although the ambient temp is 103, the dewpoint is 34. That means your ac system doesn't even need to condense water out of the air to make you comfortable. The latent heat of water is very high (hence the reason it makes a great engine coolant), so this represents the removal of a very large heat load from the ac system.

The 10F temp difference between idle and highway is normal on these older cars. The compressor just doesn't have enough output at idle to produce colder air, regardless of how well the evap and condenser are working.

On your data above, was one drive early in the morning and the other with the sun overhead? The difference in vent temps could well be due to the difference in solar load (i.e. infrared heat) the car is absorbing.

How confident are you the recirculate actuator is working correctly? The 124 has 3 recirculate positions - 0% (fresh air), 80%, and 100%. The vacuum actuators - there are two for recirc function - have two seperate vacuum chambers. Applying vacuum to both delivers 100% recirculation. The portion of the actuator that takes it from 80% to 100% seems to fail more frequently. Perhaps you have only partial reciculation? It's easy to check if you have a handheld vacuum pump with a guage.

Finally, how clean is your evaporator? IMHO much of the improvement I saw after replacing everything on my 124 system was because it had a clean evap, where none of the fins were blocked or coated with insulating dust and dirt. Quite simply, the new evap had the ability to absorb much more heat from the airflow over it. These early 124 cars don't have cabin air filters, so the evap tends to get rather crudded up.

Enough rambling for today,

- JimY

ps2cho · #19 06-23-2012, 09:08 PM

1) I have cleaned my evap, but when I pulled it here was how it looked -- as you can see, pretty clean surprisingly:
Also, when I pulled on the actuator via the door, I heard hissing, so I know its working, but maybe the 80% setting is not? I'll have to pull the glovebox to test it I guess.

---

2) So are you saying the later model W124's do not use a parallel flow condenser? The only difference is in the in/out port locations? They do look similar...I just "heard" that the later models used the parallel flow for the improvement in efficiency.
1994 E320 Condenser:

1988 300TE Condenser:

3) Lastly, what exactly makes brand new cars' A/C so much better than our old systems? I mean the main principles are the same, so is it just something like bigger compressors/condensers/evaporators?

jcyuhn · #20 06-24-2012, 11:49 AM

I think it'd be worth your while to check the vacuum actuators. It's about a 30 minute job, assuming you have a mityvac. Check all 7 and let us know what you find.

I've owned and serviced both early and late 124 cars. The condenser on both looked very much the same with the only difference being the location of the inlet/outlet to accomodate the differing manifold hose assemblies.

A couple of things are different on new cars. They use parallel flow condensers from the factory. They have gigantic electric fans to move air over the condenser and radiator. Have you ever heard a late model Benz spool up into maximum cooling mode - it sounds like a jet taking off. Finally, and perhaps the most significant, is that new cars use variable displacement compressors. This allows them to keep the low side pressure at the ideal ~30lbs across a wide range of airflow, heatload, engine RPM, etc. which provides better cooling, especially at idle.

ps2cho · #21 06-24-2012, 10:26 PM

I will go buy a mityvac and test the actuators next week.

So to wrap up, there is no size difference, or design difference between the two condensers other than port location?

What about an alternative single fan upgrade to the stock one that would push a lot more air?
and what about finding a condenser from a later model that is parallel flow?
Maybe I'll pop my girlfriends hood on the CLK320 and measure her condenser size.

JamesDean · #22 06-24-2012, 10:31 PM

I'm a bit late to the discussion but have you considered replacing the main (belt driven) radiator fan with a big electric one?

ps2cho · #23 06-24-2012, 10:37 PM

Engine cooling is not really an issue, its the condenser temp. If I keep the A/C off, even at 110C, engine temp is like 90C. With A/C on, it'll add 10C or so, even on the freeway.

JamesDean · #24 06-24-2012, 10:41 PM

Quote:

Originally Posted by ps2cho

Engine cooling is not really an issue, its the condenser temp. If I keep the A/C off, even at 110C, engine temp is like 90C. With A/C on, it'll add 10C or so, even on the freeway.

The big fan will be an electric puller fan, so it will help cool the condenser as well as the radiator...I would think. I would only try it after you've swapped up to dual fans and you find that they are not quite enough.

compu_85 · #25 06-24-2012, 10:46 PM

Quote:

Originally Posted by JamesDean

The big fan will be an electric puller fan, so it will help cool the condenser as well as the radiator...I would think. I would only try it after you've swapped up to dual fans and you find that they are not quite enough.

If you installed a good puller fan you could dump the pusher fan up front. I hear the ones from 90s Ford Thunderbirds are about the right size and move a lot of air.

-J

ps2cho · #26 06-24-2012, 10:52 PM

I was doing some reading through this thread:
Condenser size (AC condenser)
and...
http://www.a1electric.com/spal/faninfo.htm

So I think I need to concentrate on getting the temperatures down on the freeway first -- aka the fans are pointless changing first since it struggles to cool on the freeway regardless. If I can get the condenser to cool down on the freeway, I can tackle the fans later.

Thanks for the information guys it helps me figure out what I need to do.

I'll consider switching to the big electric fan in place of the fan clutch too.

Zulfiqar · #27 06-25-2012, 10:51 AM

According to an old mechanic - the engine fan should take care of nearly all the heat load, the fan upfront the condenser is just to help the main fan heat up and engage to pull air.

I saw a very strange looking shroud on some W124 300E in UAE, it was not original, it was 2 pieces top and bottom with buckle clips and a yellow warning sticker on it that said - engine fan, which made the fan sit quite deep in the shroud. The shroud was installed to cope with the additional "crazy" heat load that UAE sees, and according to the owners it did work.

jcyuhn · #28 06-25-2012, 10:51 AM

Don't forget to take into account the capacity of your electrical system and alternator when converting to an electric fan. Newer Benzs have 150 amp alternators. I don't recall what is on the 124, but not sure it's much more than half that size.

You've probably found ackits.com on the 'net, but just want to mention it here. They have bunches of generic parallel flow condensers to choose from. I think they are even local to you.

And the same google search that turned up ackits dug up this thread, which has the results of my 124.193 wagon ac rebuild. It's 8 years old, but has facts and figures on 124 discharge temps and high/low side pressures with R-12 and R-134a. 1982 300TD R134a conversion with parallel flow condensor update!!

Cheerio,

- JimY

Zulfiqar · #29 06-25-2012, 10:52 AM

According to an old mechanic - the engine fan should take care of nearly all the heat load, the fan upfront the condenser is just to help the main fan heat up and engage to pull air.

I saw a very strange looking shroud on some W124 300E in UAE, it was not original, it was 2 pieces top and bottom with buckle clips and a yellow warning sticker on it that said - engine fan, which made the fan sit quite deep in the shroud. The shroud was installed to cope with the additional "crazy" heat load that UAE sees, and according to the owners it did work.

@ps2cho.

You should look into the heater valve too. The original system has a bleed that if allowed to constantly bleed will cause the heater matrix to heat up.

Air&Road · #30 06-25-2012, 11:30 AM

Quote:

Originally Posted by jcyuhn

I think it'd be worth your while to check the vacuum actuators. It's about a 30 minute job, assuming you have a mityvac. Check all 7 and let us know what you find.

I've owned and serviced both early and late 124 cars. The condenser on both looked very much the same with the only difference being the location of the inlet/outlet to accomodate the differing manifold hose assemblies.

A couple of things are different on new cars. They use parallel flow condensers from the factory. They have gigantic electric fans to move air over the condenser and radiator. Have you ever heard a late model Benz spool up into maximum cooling mode - it sounds like a jet taking off. Finally, and perhaps the most significant, is that new cars use variable displacement compressors. This allows them to keep the low side pressure at the ideal ~30lbs across a wide range of airflow, heatload, engine RPM, etc. which provides better cooling, especially at idle.

De Je Vu all over again!

About 8 years ago, I was getting too high vent temps and Jim Yuhn wrote something VERY SIMILAR to what he is writing in this thread. I ended up pulling the glove box insert and indeed finding bad recirc pods. This led to the fifteen hour job of pulling the dash and replacing ALL pods. I checked them a month or so ago and they're still good.

In the course of ps, talking about his good vent temps I completely discounted the possibility of no recirc as a problem.

Jim to the rescue again!

ps, on the one hand, I hope you find bad recirc pods so that you can find your problem. On the other hand, I hope you don't so that you don't have to pull the dash. Big job!

Best of luck

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode