FGY33 Air Conditioner better at IDLE VS the G50?

[Infinitiguy19]

I was looking at the HA (Heating and Air Conditioner) section of the FGY33 (1997-2001) Infiniti Q45 service manual. \And in this case I was looking at the 2001 Infiniti Q45 service manual. I noticed that when the engine is IDLING! it produce near the same cooling ability as when the G50 (1990-1996 Infiniti Q45) when the G50's engine is at 1500 RPMs. All other test conditions are the same Except for the rear air vents being on. Why is the FGY33 is better at keeping the vehicle colder while idling with A/C on (more than 700 RPMs)?

All test readings in the service manual are with in 1*F of each other.

So is the compressor on the FGY33 better or do the duel condesor fans help ?

I am no A/C specialist! And I am just curious because I have no desire to put a FGY33 condenser in my car.

[qship96]

Despite what many here on the boards write, the G50 has a MEDIOCRE AC system AT BEST { even when the car was brand spankin new} you are correct, the newer Q has much better specs.......go look at some FSM for other Nissan cars and this becomes extremely evident.....look at the cooling specs for the 1/2 price 2002+ Altima....the cooling specs blow away the G50 {concentrate on the expected vent temperatures at various in cabin temps, especially at 77 degrees, you will see the g50 cant come close to the much colder vent temps the other cars are capable of.....and most of these other cars produce these lower temps AT IDLE speed, NOT the 1500 rpm the g50 numbers are calculated at...........no wonder the Q takes soo long to cool down after being parked in the sun with windows closed......I have stated many times, our old Miata could produce vent temps in the upper 30s at full fan speed almost immediatly, even under these "hot soak" conditions. Not sure adding fans or even swapping condensers would do much for the Q, as the evaporator is really not large enough to take much advantage of these improvements- you would need to upsize everything- which would be tough to do as space restrictions would be tough to overcome.......maybe one could add a second evaporator in rear deck, like some true lux cars offer.

[Skibane]

Did the G50 have a variable-displacement A/C compressor?

If not, that might explain the difference.

[elwesso]

I have to agree with qship. The Q AC system does work, but theres far better for far less money... A simple cyclical type AC compressor like most cars use work very well for a long time..

On the other hand both cars have similar compressors (both V-6 variable), so comparing idle specs to 1500 RPM specs may not be fair? I figure they changed the specs to idle because its easier to check than holding the engine at 1500 RPM...

[OwnerCS]

Here's a story about a dude who used the Maybach method by adding 300 lbs of heat and sound insulation to his diesel Hummer. I wish Maybach would send ME a pallet of auto insulation materials for the Q..

I aim to use a similar approach that has been around forever on Bentley and Rolls products -- that hopefully won't add so much weight.. I did the doors a while back..

http://flashoffroad.com/Improvements/In ... proof.html

[Infinitiguy19]

OwnerCS how would you add more power to make up for the extra weight?

94-96Q A/C system is average at best{even when the car was new} compared to many other cars- if Q is heat soaked from being parked in hot sun, it indeed takes too long to start blowing really cold air as compared to many other cars.Our old 1999 Miata could blow 34 degree air on high speed blower almost immediately in same heat soaked conditions.

Tinting the windows with a quality ceramic based tint{Formula One Pinnacle, Huper Optik,etc} helps, and the real heat blocking trick is covering that huge expanse of glass known as the windshield with the recently released 3M Crystalline heat rejecting film{ technically illegal in most states, but it is so light at 70% it is un-detectable to the roving tax collectors} Best investment you can make to improve your comfort.....without the heat blasting through the front windshield, it feels like driving in cloudy weather!!!! http://WWW.prescriptionwindshields.com

weak-ac-on-start-up-1995-q45-t442044.html?

[Q451990]

Is your FSM comparison for the G50 for a model year that came with R134a or an earlier Q with R12?

I suspect those systems would behave differently.

Heath

[Infinitiguy19]

No sir I have a 1990,1991 and 1993 Infiniti Q45 manual (Paper version). I used those as a comparison.

[BadQ45t]

Plus the older systems were colder, my Z when it works gets colder and my old 85' Maxima used to get rice cold. That old fashioned stuff that was killing the envrionment worked really really well.

[OwnerCS]

OwnerCS how would you add more power to make up for the extra weight?

94-96Q A/C system is average at best{even when the car was new} compared to many other cars- if Q is heat soaked from being parked in hot sun, it indeed takes too long to start blowing really cold air as compared to many other cars.Our old 1999 Miata could blow 34 degree air on high speed blower almost immediately in same heat soaked conditions.

Tinting the windows with a quality ceramic based tint{Formula One Pinnacle, Huper Optik,etc} helps, and the real heat blocking trick is covering that huge expanse of glass known as the windshield with the recently released 3M Crystalline heat rejecting film{ technically illegal in most states, but it is so light at 70% it is un-detectable to the roving tax collectors} Best investment you can make to improve your comfort.....without the heat blasting through the front windshield, it feels like driving in cloudy weather!!!! http://WWW.prescriptionwindshields.com

weak-ac-on-start-up-1995-q45-t442044.html?

LOL --- Well I've lost 30 lbs since I bought the Q (from working on it all the time in the heat) -- so that will help..

I'll look into the windshield film.

[TellarHK]

I just had an R134a A/C system essentially installed from scratch in a '90 300ZX, and let me tell you guys - it was an expensive pain in the a**. After spending about 3 days in the shop, I got it back only to find that they hadn't actually _done_ a new system built for 134a, they used "freeze 12" instead. Considering that I had an estimate, and a receipt telling me they were doing - and charging me for - 134a, I had them fix it. Fortunately they didn't give me any hassle as the manager realized the technician screwed up by simply not communicating with anyone. Another two days later, and we had a proper 134a system running - and colder than "freeze 12".

So, what should I do when the Q finally needs a system recharge or fix? I know it's running "decently" now with R12, but it seems increasingly hard to get R12 anywhere on the planet. Is it something I should be looking for, or should I just get it converted anyhow?

I don't care enough about the environment to want to give up my R12. Just sayin'.

[elwesso]

Honestly I used freeze 12 in my old BMW just to top it off, and it works really good. I dont think it was as good as R12 but it was better than no AC.

Personally in your case if you have to evacuate and recharge for some reason, I would just convert it to R134.. You dont really need to change much, just a new dryer (you'd need to do this anyway if the system was opened), and flush it out to get the old R12 based oil out of the system.

[qship96]

No sir I have a 1990,1991 and 1993 Infiniti Q45 manual (Paper version). I used those as a comparison.

Paul, what are the expected vent temps listed at 77 degrees blower input on the 90-93Q as per the manual ??

The later 94-96Q with r134a lists 48-52 degree vent temps at 77 degree input.{Which is pathetic}

[qship96]

I just had an R134a A/C system essentially installed from scratch in a '90 300ZX, and let me tell you guys - it was an expensive pain in the a**. After spending about 3 days in the shop, I got it back only to find that they hadn't actually _done_ a new system built for 134a, they used "freeze 12" instead. Considering that I had an estimate, and a receipt telling me they were doing - and charging me for - 134a, I had them fix it. Fortunately they didn't give me any hassle as the manager realized the technician screwed up by simply not communicating with anyone. Another two days later, and we had a proper 134a system running - and colder than "freeze 12".

So, what should I do when the Q finally needs a system recharge or fix? I know it's running "decently" now with R12, but it seems increasingly hard to get R12 anywhere on the planet. Is it something I should be looking for, or should I just get it converted anyhow?

I don't care enough about the environment to want to give up my R12. Just sayin'.

If you have a 1994 q45, like it says in your signature, you already have r134, NOT r12.

[Q451990]

No sir I have a 1990,1991 and 1993 Infiniti Q45 manual (Paper version). I used those as a comparison.

So you're comparing an R-12 system with a 134a system... which might account for the difference.

Heath

[Infinitiguy19]

No sir I have a 1990,1991 and 1993 Infiniti Q45 manual (Paper version). I used those as a comparison.

Paul, what are the expected vent temps listed at 77 degrees blower input on the 90-93Q as per the manual ??

The later 94-96Q with r134a lists 48-52 degree vent temps at 77 degree input.{Which is pathetic}

At 50%-60% relative humidity and with a ambient temperature of:
77*F yields 46*-50*F from the vents
86*F yields 51*-55*F from the vents
95*F yields 55*-61*F from the vents
104*F yields 60*-66*F from the vents

60%-70% relative humidity and with a ambient temperature of:
77*F yields 50*-54*F from the vents
86*F yields 55*-60*F from the vents
95*F yields 61*-66*F from the vents
104*F yields 66*-72*F from the vents

The above results are with these conditions:

Doors: Closed
Door window: Open (Front Left ONLY)
Hood: Open
Auto switch: On (HVAC (A/C and Heater) Controls)
Down arrow switch (P.T.C): Max. COLD set (65*F)
Recirculation switch: On (Set)
Fan switch: Max. Speed set (All four fan blade lit up)
Engine speed: 1,500 rpm
Time required before starting testing after air conditioner starts operating: More than 10 minutes.

I feel like I am in elementary school again after school writing on the board "I will not do stupid things" (Bart Simpson).

[qship96]

Ok, that proves the later 94-96Q r134a based system is slightly worse than the 90-93 R12 based system.....the specced vent temps are 48-52 degrees at 77 ambient {passenger footwell} at 50-60% humidity VS the 90-93Q s 46-50F vent temps using exact same measurement test procedures!!!!! Actually they both suck compared to later Nissan/Infiniti cars specced temps.

[Infinitiguy19]

The test from my last post was taken from a 1991 Infiniti Q45 service manual.

Maybe one could add a second evaporator in rear deck, like some true lux cars offer.

Can you please go into further detail?

[qship96]

some cars, like the Audi a8, lex LS ,and even really old {1960s} cadillac/lincoln offered true rear a/c that was independent from front a/c- there is a second evaporator in rear trunk that blows cold air to rear seat passangers.....much more effective than just putting vents in rear console like later Q cars

[elwesso]

nissan presidents had a rear evaporator where the package shelf is on US G50s.

[qship96]

nissan presidents had a rear evaporator where the package shelf is on US G50s.

I thought that was just an "air cleaner" electrostatic /mechanical filter element?

[Infinitiguy19]

http://picasaweb.google.com/lh/photo/ig ... directlink

some cars, like the Audi a8, lex LS ,and even really old {1960s} cadillac/lincoln offered true rear a/c that was independent from front a/c- there is a second evaporator in rear trunk that blows cold air to rear seat passangers.....much more effective than just putting vents in rear console like later Q cars

With all the things I want to do (Including hit the lottery) I would think importing a Nissan President would be the best thing to do. The Nissan President had rear air vents but no duel heater core of evaporator.

Give me a Nissan President (1989-2001), 100K worth of tools, a shop with a lift (Should be included in the 100K worth of tools but I am stating it so people can know) and I will give you the best Q45 in the world! No promises on the time to completion but I would'nt leave the shop till its done. Hell I might do it for free knowing I could drive the car because I love working on Q45's.

Dreams...

[TellarHK]

If you have a 1994 q45, like it says in your signature, you already have r134, NOT r12.

Okay. I checked it after seeing this post today, and... yeah, I screwed up. I thought it was R12, because the fittings appear to be R12 style with the screw connectors. But, nope. It's R134a according to the actual A/C identifier on the strut tower. I'm much happier knowing that, now.

[Infinitiguy19]

I had another bright idea yesterday...Would increasing the idle when the A/C is on in Park/Neutral (P/N) and in drive help with the cooling issue?

It can easily be done for sure but I want to know if it would help. And I would say to be safe as far as the transmission is concerned I would only go to about 800 RPMs.

Sorry if this has been asked before but I know a couple of more things that the Infiniti engineers didn't think of or didn't want to implement due to cost....These are recent idea's too.