vintage air short cycles

[AcampoDave]

I put the sure fit kit on my 66 it is properly charged as verified today by a trusted shop. They say it needs more air flow over the condenser at low speeds. I have a 6 blade flex fan spaced half in half out of my factory shroud with a good radiator. (It doesn't run hot.) Also have all my baffles and air seals in place . I'd prefer to stay with a mechanical fan. ( I am not opposed to buying a clutch fan if I knew which one to buy) Do you guys think it's a good idea to make a seal of some kind to go around the perimeter of the condenser? My thinking is this would force the fan to pull thru it 100%. Currently there's an open space of about an inch between the radiator and the condenser and I wonder if my fan just pulls air thru the gap instead of thru the condenser. Also, is anybody using a clutch fan they can recommended for an a.c. application? Thanks

[clinebarger]

Originally Posted by AcampoDave

I put the sure fit kit on my 66 it is properly charged as verified today by a trusted shop. They say it needs more air flow over the condenser at low speeds. I have a 6 blade flex fan spaced half in half out of my factory shroud with a good radiator. (It doesn't run hot.) Also have all my baffles and air seals in place . I'd prefer to stay with a mechanical fan. ( I am not opposed to buying a clutch fan if I knew which one to buy) Do you guys think it's a good idea to make a seal of some kind to go around the perimeter of the condenser? My thinking is this would force the fan to pull thru it 100%. Currently there's an open space of about an inch between the radiator and the condenser and I wonder if my fan just pulls air thru the gap instead of thru the condenser. Also, is anybody using a clutch fan they can recommended for an a.c. application? Thanks

For the Head Pressure to get high enough to cycle the Binary at 400 psi you have a serious issue.

Did you add any oil to the system? Sanden Compressors come Pre-charged.

Get a set of gauges, Over 300 psi is the danger zone.

No Vintage Air system needs more the 2 pounds of Freon, So how much Freon is in it?

Not sure on the Flex Fan, They are dangerous & should not be used......On anything.

[AcampoDave]

It has 1.86 pounds and pressures checked at 260 high and 50 low. No extra oil added and copy that on the flex fans

[65truckowner]

I have a vintage air in my 79 bronco and it sounds to me like your low pressure is to high.

[AcampoDave]

I agree about the low side. Would that go alng with the airflow theory?

[LT1 Burb]

Higher low side equals higher high side, maybe a metering device issue. There is no way you can be getting 40 degree air off of that evap. Any evap air in and air off temperatures and what is the condenser pressure and entering air temp temp of condenser.

[AcampoDave]

Lt1burb, I dont know about air in and air off, but the ambient air temps are in the 90's around here still. The a/c is basically new, and at first seemed to act up worst after I shut down for a few minutes and let the underhood temps rise, then fired the motor and drove. It cycles like 3 seconds on and 3 seconds off. Now however, it will also do it when I'm just driving along sometimes too.

[65truckowner]

I would say your freon level is not right. Sounds like you have too much.

[Jeff La]

Did you get the low side reading when it was cycling. It sounds like your low side is taking you out from not enough freon.

[65truckowner]

On mine when I was getting it charged the low was a little low and the ac guy added a little more freon to raise the lower side which also raised the high side. So if you had too much would that not make the low side too high?

[brokenspoke]

Ditch the flex fan....Have you called Vintage Air?

[AcampoDave]

Called V/A and the problem was diagnosed as a low speed airflow problem with regard to the condenser. Today I made a good rubber seal where my shoud meets the radiator filling the air gap, and blocked the space at the bottom of radiator and condenser. I felt too much air was getting sucked up from below in the space between the two. Lastly I upped my idle a few hundred r.p.m. I took a test run and it worked fine. It was only 90 degrees out today ( a bit cool for a real test) but I think I'm good. Anybody got a clutch fan recommendation?

[luvbowties]

Originally Posted by AcampoDave

Called V/A and the problem was diagnosed as a low speed airflow problem with regard to the condenser. Today I made a good rubber seal where my shoud meets the radiator filling the air gap, and blocked the space at the bottom of radiator and condenser. I felt too much air was getting sucked up from below in the space between the two. Lastly I upped my idle a few hundred r.p.m. I took a test run and it worked fine. It was only 90 degrees out today ( a bit cool for a real test) but I think I'm good. Anybody got a clutch fan recommendation?

I'm not too keen on ac. But, I do have experience with clutch fans, flex fans, and solid mount fans. Altho' the solid mount can make excessive noise(roars), they pull considerably more air than flex or clutch fans. As cheap as one should be, I'd surely experiment with a 6-blade(or more blades), solid mount fan, just to see what happens when the extra air is pulled thru the condenser: this should never amount to much of a loss or waste of $. **I think your spacing between the present fan and shroud approaches ideal, & I'd strive to keep it there.**

I dunno how far the condenser should be placed in front of the radiator, but seems like 1 inch may be a bit excessive. Can you move it to where it leaves approx. 1/2-inch between the two? Whichever you experiment with, I believe a seal between the two would force significantly more air thru the condensor at low rpm's--surely these changes should meet the suggestions of VA-reps.

Overall, I'd guess your problem will end up with a simple solution. Don't waste $ on clutch fans or electric fans--at least in the beginning. Other than a bit of roar, the 6-blade[**7 or 8-blades would not hurt either: IIRC, I recently saw, at a pull-a-part yard, like an 8 or 12-blade fan on a 2500 series Chevy, that may have been of composite, yet very solid blades, in a solid mounted fan.**] will definitely pull max. air thru the cond. & should solve your problem--IF VA is right, and I'd say they are giving knowledgeable advice.

Good luck with solving your ac challenges; and please keep us informed, as I wish to soon add ac to my '66, and I need all the info/advice available, as I don't desire to re-write a HOW-TO ON AC FOR '60-'66 CHEVROLETS.

Thx in advance for all the feedback and insight and suggestions you can offer us novices.

Sam

[AcampoDave]

Yesterday at a car show I noted most condensers as being closer to the radiator than mine, but the surefit kit puts mine in front of the core support to allow room for the dryer and hard lines. Moving the condenser backward looked far more difficult than closing the air gaps. The shroud gap is sealed with a weather strip from a C-10 rear window at the top, while the space between the condeser and radiator at the bottom is minimized with a simple metal flashing secured to the lower horseshoe radiator mounts using the stock hardware. My fan is driven by an underdrive pulley listed as stock for a '60 Impala w/ a.c by Mr. Gasket. With the new air control measures I have rigged up, the sound of my fan has changed to a deeper more whooshing tone upon acceleration. (Probably created by the wind tunnel effect of a sealed shroud) Yesterday's drive of 45 minutes in 87 degree heat yeilded a perfectly acceptable a.c. I doubt we'll see 100+ temps again until next May so as of now I will seek out an engine driven replacement for the flex fan and wait.

[AcampoDave]

I know we all love pics around here so here you go...last one is upside down due to my vantage point.