Question about retrofit using Dupont Isceon MO49 (R413)

[mariano_vina]

Hi there!
My Name is Mariano, from Argentina, i'm a hobbyist enthusiast in all car electronic related and now i'm working on refrigeration (AC systems).
Don't know if this is the correct place for this thread, but i couldn't find a specific one for car related air conditioning.

My car is an older 1993 Renault 21 with an Sanden TRF-90 scroll compressor based AC system. Original complete system uses R12 with a load charge of 0,95Kg.
Since a long time ago, try to get R12 in my country seems to be a nightmare so i was searching for a specific replacement and i've found my new friend: Isceon MO49 (R413).

Into the retrofit, orings, oil and the cleaning of the evaporator and condenser (sorry if the last 2 are not correctly writed) were included. The system was putted under full vacuum and it's leak free, and after a complete reading of all the Isceon's PDFs i have started to put the gas on the circuit.

I was read that...
- Must put into liquid phase and not over the compressor.
- Work pressure is higher than R12, so they would suggest to use between 20-25% less charge compared to R12. I have use only 0,6Kg.
- Compatible with all oils, including mineral: i have use the synthetic for R134a.

Ok, the results are:
- Between 2000 and 3000 RPM (car running with load), extremly cold air into the car, when ambient temperature is between 26°C and 30°C (seriusly, in several times i have to put it off).
- Freeze sensor cuts compressor when air temp goes to 0°C (it works fine).
- High pressure sensor start the fans at high speed when pressure rise at 300lbs (starts earlier compared with R12, but seems to work fine).
- Engine temp. is a little bit lower than normal (pretty fine).

But, in an ambient temperature between 32° and 39°C (last temp. measured past Sunday on my country):
- Cold air starts to fall (fresh air...) when car is running, with or without load, between 2000 and 3000 RPM.
- Engine temp. starts to rise.
- Obviously compressor never stops.
- Fans working continously at high speed. They never stops.

So, the question is: What is happening when ambient temp is upper than 32 degrees?
Is Isceon MO49 a problem for my AC system? or maybe there´s a wrong component?
Last summer, when R12 was working on my car, the system was working fine, but the air was not so cold, 'cause the system had a leakage (broken oring).
Condenser is clean, and the engine radiator was changed 8 months ago.
Maybe under charged?

Any help will be much appreciated!

Regards!

Mariano.

[xxargs]

Seems freezer sensor is not working correctly and evaporator frozen full of ice and hinder airflow.

0. condensor fan working?

1. faulting freezer sensor

2. missplaced freezer sensor to sense hot aiflow even if cooling works.

3. to low level of refrigerant in high load situation and refrigerant boil dry in pipes in evaporator long before evaporator outlet and TXV - if freeze sensor mounted near refrigerant outlet, sensor can sense hot air trough evaporator even most of evaporator are ice block...

If big pipe from evaporator outlet to compressor is warm or air temperature and not any cold feeling time to time (ie. missing sign of TXV working) if ventilation/fan running on max and engine working around 1500 rpm - in mostly case you missing refrigerant. if you using manometer and measure lower than 2-1.5 Bar on low pressure side more than few seconds before compressor stops, you have minus degree C in evaporator and icing up after while.

4. You have still a leak i system and you lose refrigerant


Poor mans version of 'R413' is a make blend of R134a with approx 3-5% by weight isobutan (R600a) or blend of butan/propan


R413/MO49 have 3% of R600a by weight (and have 9% R218 to eliminate small glide make from R600a) to make better oil transportation i system in system with mineral oil (poor man version blend works same way but not compensate for small glide) ie. R600a are used to emulsify oil dops from compressor to microscopic size in liquid phase of refrigerant, simulate same mechanism as fat in milk.

R218 used in R413 is not recommended in blend depend of very long atmospheric lifetime (2600 year!!!) and very high GWP value at 8830 and i think are forbidden in many countries, for example R134a have only 14 year lifetime and 1300 in GWP and still going to forbid in EU...

In environmental aspect is better to make self poor mans blend with 3-5% butan/propan and 97-95% R134a by weight compare to use R413...

Even if Argentina possible not have same hard R-gas rule as Europa - try better environmental choice as possible and for me is home blend of R134a and few percent of propan/butan better choice compare to continue using R413/MO49, and possible cheaper...

[waterskidog]

This ***** works really good as a drop in and it could have save you a lot of money.
http://maxifrig.com

[mariano_vina]

Dear xxarg,
I really appreciate your time and the extense reply! I will reply on each point

0- Yes, codenser fan are working good in both speeds.

1- I have in mind that freezer sensor cuts compressor when evaporator temp. goes to zero, so i think it works great, but i will get another one just to do a test.

2- Freezer sensor is clamped into the evaporator, just in the middle, not in the outsides. There's a special pipe in the evaporator that goes through it, just to the center.

3- Don't think that evaporator get iced when cold air starts to get fresh. Air flows still the same but, just like you said, i will check the low pressure before compressor get stopped.

4- Probably, yes, it's a possibility.

Isceon can says that there is a 88% of R134a, 9% of PFC218 (don't know what it is) and 3% of Isobutane.
Maybe the gas is the trouble...

Remembering the job that i did, i have use R12 manifolds, instead of the R134a's, and the high pressure works between 300 and 350lbs@30°C (i know that limit pressure with R12 is 300lbs.)
Could it be an overcharge?

How can I specify the propan/butan denomination? Just to buy a can, and another of R134a. Maybe a home made blend is another solution.

Waterskidog,
Thank you! I will try to get some cans of Maxifrig, the only trouble in Argentina are the duties, taxes and special, the customs boys (steal boys).

Regards!

Mariano.

[xxargs]

i think PFC218 is some ones (DuPont?) trade name for HCF218 or R218 aka octofluorpropane.

If using only 3% HC at weight in R134a i think not so big difference if using pure butane, isobutane, propane or blend of them - HC in R134a blend working for better oil transportation, not working as refrigerant - but if you want using HC-blend - try 60% propane and 40% isobutane, they have almost same pressure as R134a.