Air Condition

[davehoos]

Those barbed fittings with a couple of hose clamps are more vulnerable to failure than a new hose with swedged fittings.

As I dont know what USA datsun vehicles will be fitted with i have written in general terms.most of my customers needs is not restoration to original and we still supply new designed kits to old vehicles for the cost of repairs.i dought that some of the original compressors available on demand-i know that hitachi parts are often hard to find.we have a few of the larger versions in boxes that i wouldnt trust to work long term and as i explained the use of R12 is just not commercial in terms of price/results,i know you can purchase this in the usa.disposable cans have been ilegal here for years.

generally datsuns of this age use copper pipes with flared ends and are easily reproduced.Reuseable barbed ends to suit newer improved flexable hoses are very rare on factory pipes,a lot of hoses have no barb to hold onto using the swadge some only have 2 small machined grooves and require volcanising.we wield in mass produced ends and use hydrolic criping machine to give a factory look,for a workshop a WORKSTATION can be purchased that produce ready to bend alloy pipes with ferules[swagded] or a variety of standard ends,no wielding required.

you can use hose clamps,popular in the 70's-80's.these are often stronger and seal better.for problem aplications I have used hydrolic hose clamps.a doubled band of metal strap clamped with 6 mm bolt,inch wide..until recently we have used an italian hose system on heavy duty aplications.it is very thin wall and strong,the barb has 2 flat bands like orings,it is clamped with a reusable double clip that is common on fuel lines.

High side pressure,
you must look at this in terms of overgassing.but similar cars on similar days may give very different pressures.you have to use several gauges to get the full picture,datsuns of the late 80's use the liquid line at the TX valve.

the compressor draws in vapour and pressurises hot gas not liquid.the job of the condencor is to liquify this gas.some old nissan condencor i have here are single passage copper tube these.im guessing you may have a 3 parrallel passage type.i know some are muli pasasage but the last 1/3 of its travel bit is single,its worked out that this should be full of liquid.the job of the dryer is to filter but more importantly collect liquid to be fed into the expansion valve.in the valve it comes out the other side as atomised liquid,not gas.the A/C cools the cab by absorbing heat that is needed for change of state to vapour. the frost you see is the humid air loosing heat to the liquid to the point that air born water freezes.
adding an accumilator[tank/chamber] to the either side of the compressor is a common practice to reduce noise and improve compressor life at extream operation.as small as half cup to a full half gallon.some simply use long larger dia hoses looped.

Leyland workshop manual quotes 50% humidity,it like most australian manuals quote information explianing how in high humidity these sysems work much better producing lower temps.provided that they cycle out.they use the water to increase heat exchange process however the frozen water insulates the heat in the air from metal of the evap.its important to keep air moving through as the plastic box and ducts tend to sweat.the therory is that on recirc air in the cabin will be low humidity allowing lower temps.

thermostate GAP [hysteresis?] needs to be ajusted to suit the user needs.

older workshop manuals rarely quote at vent temp.this allows for lots of warranty compliant customer hassels.the modern systems i refer to and recomend you steal ideas from have evolved to improve comfort and user health.fungas/bacteria growth.
over a long trip the vent temp will drop provided the heater or the engine bulkhead or other heat transfer is minimal.
-6c metal temp[22Psi] is aprox 5 cel vent temp or 1-2 cel air temp at the evap.this ay be as low as 2cel on a good day.i find most factory setups open the expansion valve to allow hot liquid into the evaporator.SUPER HEAT SETTING.R134A will handle -18cel,i have an icemaker at work to fix that does -43cel easy.

Leyland manual Quotes
95F day-35 to 45 F vent temp.50% humidity at 1500RPM.
5-18 PSI low-185-205 HI

[philip]

SNIP- As I dont know what USA datsun vehicles will be fitted with i have written in general terms. SNIP

Generally datsuns of this age use copper pipes with flared ends and are easily reproduced.

American spec 720 trucks with factory a/c got aluminum lines with swaged fittings.

Reuseable barbed ends to suit newer improved flexable hoses are very rare on factory pipes SNIP

Why do you suppose that is? The ONLY times I've seen those goofy ends is on low dollar aftermarket retrofit a/c systems. Feruled with swaged ends are more reliable.

High side pressure, SNIP-
the compressor draws in vapour and pressurises hot gas not liquid. SNIP

Looks like another miscommunication. IN OPERATION, what you say is accurate. However, earlier I referred to the FSM process of statically recharging an evacuated system with liquid refrigerant through the HI side valve only. Since a can of R-12 is about 60 psi and the evacuated system is at almost perfect vacuum, the moment liquid refrigerant passes the Schrader valve, it turns to vapor if not gas until more refrigerant is added. Further liquid charging will result in liquid placement near the compressor's discharge port and headed to the condenser.

The job of the condencor is to liquify this gas. some old nissan condencor i have here are single passage copper tube these. im guessing you may have a 3 parrallel passage type. i know some are multi pasasage but the last 1/3 of its travel bit is single. its worked out that this should be full of liquid.

Datsun 720 truck in US has single passage flat aluminum tube condenser that coils back and forth 12+ times.

SNIP- The frost you see is the humid air loosing heat to the liquid to the point that air born water freezes.

Frost does not accumulate on the evaporator exit line in most systems regulated by an expansion valve unless there is too much oil present causing a restriction. The line should "sweat" like crazy but not frost. Now if a suction throttling valve were present, then frost accumulation at the evaporator outlet would be expected at times.

SNIP-
older workshop manuals rarely quote at vent temp.this allows for lots of warranty compliant customer hassels.the modern systems i refer to and recomend you steal ideas from have evolved to improve comfort and user health.fungas/bacteria growth. SNIP

Ok so to you an "accumlator" is an additional volume cannister that is strategically placed to act as a pressure/vibration dampener. Is that accurate? Earlier I got the impression you meant a condenser to be an accumulator.

Bacteria/mold growths seem to be a problem with drivers who operate the A/C system in RECIR mode all the time. Certainly less of a problem when operated in FRESH mode and in arid climates.

-6c (21°F) metal temp (22psi) ... is aprox 5°C (41°F) vent temp or ... 1-2°C air temp at the evap. This may be as low as 2°C on a good day. SNIP-

Thank you for identifying the effect of location on various readings! But again, the matter of evaporator core icing comes up when you have evaporator core metal temperature at 21°F. In the 1982 Datsun's case, there is a bimetal thermo swtich and circuitry to turn OFF the compressor when evap core temperature approaches 32°F. Now in 1983 or 1984, the evaporator coil construction was dramatically changed and the thermo switch was recalibrated to cut OFF the compressor at a higher core temperature (43°F). My guess is evap icing complaints.

[davehoos]

flat aluminum tube condenser-
about inch wide?and about inch between runs.
these condensors are normally multi passage,and if a few are blocked they still will work.

factory air D21 sold in australia are diesel-kik/zexell/calsonic but locally sourced.untill mid late 80'sthey had block valve in the engine bay.we often adjust the super heat setting as it sticks out on end and is easy to get pliers on to.
It has the mechanical rancho thermostat.its not calibrated out of the packet.the evaporator case is assembled ready to install with the adjustment under the white cover easy to get at.this adjustment is up to the installer to follow the kit instructions.

.the japanese imports of the early 1980's use a thermister and amplifier.I had to fit both to my R31 as on a long drive it frosts up.some cars have a thermostat attached to the evaporator outlet.when the unit freezes this by default has an auto defrost function.

i found the vent temp specs for 910.it is a copy of the japanese manual and has no relivance to the local built model.i found the same specs printed in the KN13 EXA manual.testing after 10 minutes at 1500 RPM center vent temp.at ambient 77F 40-80% humidity=48-58F
i would expect 41F.

[philip]

flat aluminum tube condenser-
about inch wide?and about inch between runs.
these condensors are normally multi passage,and if a few are blocked they still will work. SNIP

In this case, no. The tubing is a single serpentine path to the exit point ... not a dozen or so parallel passes. I noticed this when I replaced the condenser due to irrepairable fracture near the inlet.

I found the vent temp specs for 910.it is a copy of the japanese manual and has no relivance to the local built model. i found the same specs printed in the KN13 EXA manual. testing after 10 minutes at 1500 RPM center vent temp. at ambient 77F 40-80% humidity=48-58F
i would expect 41F.

Here are the prerequisits for evaluating A/C performance from the 1982 Datsun FSM. Take a look:

[asavage]

YOKE or Hitachi compressors through '83

Diesel-Kiki in '84

More?

[philip]

My system sprung a leak. I've got all R-12 servicing equipment so finding this sudden leak wasn't too difficult.

The YOKE compressor has two ports with O-ring seals. The Hi/Lo hoses are siamesed to an adaptor and secured by a single bolt. In my view this design is vulnerable to the SD's vibration.

Anyway, the odd thing here is the system would hold 29" vacuum for 30 minutes but ... would blow out under only a few pounds pressure. The O-ring on the discharge port was the leaker, yet un-torn. I replaced ALL the system's O-rings 2-1/2 yrs ago.

I'll get slightly thicker O-rings this time.

[davehoos]

I ve not seen a YOKE compressor.
lots of different ideas of sealing this area.if its a tappered seat recess in the top the oring must be larger than normal in section.if it sit in a machined groove and the adaptor is flat like the GM types you have to get the exact oring made from exact material.[ie nylon]

with most orings using mineral oil or ester type oil{r12}will soften the oring,gas pushes past intermitantly.its common to have a gas leak in this situation with no sign of oil at the joint..over time the oring melts or explodes fron inside.

[philip]

I ve not seen a YOKE compressor.

Here ya go, Dave. YOKE VR4709 compressor. Interesting side note is this compressor came in a YORK/Nissan box new.

-SNIP-you have to get the exact oring made from exact material.[ie nylon]-Snip- ... with most orings using mineral oil or ester type oil{r12}will soften the oring,gas pushes past intermitantly.its common to have a gas leak in this situation with no sign of oil at the joint..over time the oring melts or explodes fronM inside.

Sealing o-rings (packing) are air conditioning specific materials ... not just ordinary rubber or nylon. Additionally, the section can be oval instead of round (ie, HNBR neoprene material/type). Dave, considering lubricant circulates with the refrigerant, I've never run across an established refrigerant leak that was not marked by evidence of oil leakage. Of course if the vehicle is operated in a rainy environment or the owner likes a clean engine bay then this tell-tale may well get washed away before attracting dirt.

[davehoos]

common practise here now to put UV die in systems,some suppliers mix it in the gas.we are having dramas with incompatibility some systems and material.

often a car will present with low gas over a 3 month period and no signs of leaking.classic is late model cars with thin wall alloy pipes.aprox 30% of the oil is circulating in the system and coating the walls.most is in the evaporator and dryer...when i did my trade it was instructed that the oring was to prevent oil escape and the metal to metal contact sealed the gas,this is not always the case now.those snap together fitting depend 100% on orings.have a good look at the mating surface.2 yrs is good for a R12 car now.
air cavity created in the design will also prevent oil leaks,taking a large quantity of oil to fill the joint before being forced out.

I have seen these compressors,they go straight in the bin due to the cost of repairs.I dont think they are common.mazda?.from the generic shape i guess thats why it model number is :V.looks like a vane pump.R4[GM pump size] 709 style mount.

the name "yoke type" has come up in discusions about portable fridges.

its not unusual for a company to put a deal together to supply kits for a dealer network or workshops.for whatever reason they may substitute items.local content or contractual obligations.the hose cluster looks like standard diesel kiki bits.
from the late 70 to early 90 nissan australia use diesel kiki/zexell piston pump and they dont use hose clusters.

I worked on a N15 pulsar recently it had a old zexell piston pump mounted to a fabricated bracket,a locally made hose cluster was use to conect to the gen nissan fittings on the evaporator and condensor,tx was different,the kit must have been supplied as a cheeper genuine option on the FREE AIR models with a parts label added on the hood.
Worked a lot better than the japanese supplied kits.

[philip]

common practise here now to put UV die in systems,some suppliers mix it in the gas.we are having dramas with incompatibility some systems and material.

Same over here. The Wise HVAC has an electronic sniffer.

SNIP- when i did my trade it was instructed that the oring was to prevent oil escape and the metal to metal contact sealed the gas,this is not always the case now.those snap together fitting depend 100% on orings.have a good look at the mating surface.2 yrs is good for a R12 car now.

This Datsun has a mixture of o-ring dependent fittings and flared fittings with an o-ring redundancy. Has to have been spare parts or contractural agreements.

SNIP- I have seen these compressors,they go straight in the bin due to the cost of repairs.I dont think they are common.mazda?.from the generic shape i guess thats why it model number is :V.looks like a vane pump.R4[GM pump size] 709 style mount.

I've never seen another application for this particular pump and even then, only the first year 720 trucks with a diesel got them. There is another manufacturer who makes a nearly identical compressor but the name and model escape recall right now.

SNIP- I worked on a N15 pulsar recently it had a old zexell piston pump mounted to a fabricated bracket,a locally made hose cluster was use to conect to the gen nissan fittings on the evaporator and condensor,tx was different,the kit must have been supplied as a cheeper genuine option on the FREE AIR models with a parts label added on the hood. Worked a lot better than the japanese supplied kits.

Not so this system. When charged correctly and with the odd TX and tubing evaporator it has, it throws out an artic blast on the hottest of days.

[philip]

The O-ring on the discharge port was the leaker, yet un-torn. I replaced ALL the system's O-rings 2-1/2 yrs ago.

Follow up

In moving the siamesed Hi/Lo hoses at the compressor, I created another leak. The Hi pressure hose leaving the compressor connects to an 8" long "L" pipe that in turn connects to the condensor inlet. This "L" pipe is o-ringed on both ends. The condensor end uses an o-ring that slips over the aluminum tube and butts up against a shoulder. It was this shoulder where refrigerant started leaking ... where it wasn't leaking earlier. Electronic halogen detectors are the greatest.

Found another "L" pipe at the junk yard from an '84 gasoline truck. While having the same fittings and same overall length, the shape was quite a bit different. So... I reshaped it (cringe!). Worked!

[davehoos]

YOKE compressor. boss thinks they are CENTRAL copy or rebadged.
found reference to it. VR4709 YORK 7 inch compresssor, equal to nipondenso rotary van. in the scrap bin is a central vane pump off a 610-810[L18-L20B] looks the same except the center body is round like the later DKV14. it has the standard oring fittings with the service valve layout of your compressor. no longer serviced.

not always but i thought a spigot of some type on the manifold.

in the bin i found a zexell DKS-15B look-a-like. not a tama but a UNICLA. this was off an 810. a manifold on the rear with standard outlets pointed down and 2 short alloy pipes bent at near 180 to bring them back up top.

sniffer is good, BUT if your trained to use them, lots of false readings and can be frustrating. worth the money for a business. we have 4 at work and you find that you can often use 2 on one job..at work on a normal day I can test and quote 10+ jobs a day.

[philip]

SNIP- Sniffer is good, BUT if your trained to use them, lots of false readings and can be frustrating. worth the money for a business. -SNIP-

Then let me bring you up to speed, Dave. With the price of R-12 being $15-25 (USD) per one pound can and the inconvenient delay in getting R-12 delivered, an electronic halogen sniffer is INDISPENSIBLE. These things can be purchased slightly used on eBay for under $35 ... though you can pay much more if you so desire.

There is nothing frustrating about using a sniffer after you read the instructions ... which tell you that other fluids (like ethylene glycol engine coolant) are capable of setting off the alarm. I have a CPS brand sniffer that is much too sensitive and a Snap-On (5500) that is a "reasonable" sniffer .... and my preferred tool.

[philip]

Philip,

I whish you the speediest recovery. I am sure that I am not alone when I say that I am always looking for your comments first when I visit this site

Hey. A week+ ago I bought a halogen leak detector at eBay ($20)! It weeked on wednesday ... the same day by Saint Joseph brought me home. This is a one must teaching a freon R-12 (also R-134a) correct.

Anyway, the ol Datsun runs COLD again. 37* real cold. I'll try what broke an o-ring and what broke a crack in aluminum tube. Weird.

(later)



This tube was for a 1981/82. I could not find another but ... I found a later ones for 1983+. But this newer tube twists the later bent. So I fixed it! Hey ... LOL

[ecomike]

I'm thinking it's about time for this become a HOT topic, LOL.

I know this going to kick Philip into high gear, but as they use to say, here goes nothin.

Philip has said in the past that the original condenser and compressor are undersized for switching to R-134a, from the original R-12. Mine is a hybrid, part Nissan compresor (SD-508) part Jeep (everything else). It turns out the SD-508 was also used on the Jeep XJ's, Cherokee's (Mid sized Jeeps).

I am not convinced the condenser and compresor are the real problem. First though, I must agree that R-12 gets colder and works better, no doubt about.
But for those of use that have or do make the change, I have an alternate idea I am going investigate. That idea is that maybe it's the expansion valve that is the underisized when switching to R-134a!

I am going to inquire of some full time A/C mechanics in another forum and see what they say. My theory is based on gauge pressures I have seen with the R-134a. A slightly larger flow should produce a bit more cooling, and I do think (at least in my case) that the compressor and Condenser I have are not undersized.