Help with 1976 Chevrolet K10 A/C

[jfkelley]

I have an 1976 K10 Scottsdale 4X4, The A/C has been retrofitted it blows Semi Cold when Idling , But if I give it gas while sitting still the blower speeds up and blows cold, Also when you drive it you can hear it start blowing harder and its gets colder..A/C has been charged , All Ducts been inspected and are good..Do I need a new Clutch fan or Blower Motor ? Maybe one out of an 1994 Truck?..Plus the A/C Blows Max regardless what setting you have it on low medium ..Its HOT in Oklahoma right now 118 today...Any Help or Advice would help ...Thanks

[Tom Greenleaf]

I recall these that had A/C at all where I am as the Suburbans, single/front A/C only should be close enough. Of all things to miss if A/C stinks and blower is slow then speeds up and cools down more with I think more RPM than speed the belt(s) could just be loose!
Both turning compressor more and alternator more you speed up a blower with the higher voltage. Maybe all wet but all those belts (a few at least) as manually adjused some can depend on one for the real tension on the next done in order.

Guessing a small block V8 you didn't say. Clutch is always important should be fine if just a good one roar a bit at take off and calm down with road speed if not get a good thermostatic one was plenty OE or retrofit.

Blowing "Max" only? It's so old now if you can just put up with that till total off season do so I think brass on brass contacts on slide "rainbow" looking thing where you select what you want is worn! Not fixable but you might if taken all apart AYOR or ruining it.

Why would you want less then max? You have vent windows and air is change passively anyway every minute or two in this look at the vent thing on door jams is what those are for. I just mean asking for outside air thru HVAC box it just overworking it you get fresh air anyway.

Check alternator belt not sure of belt set up depends on engine. A/C compressor may be it's own belt or not propably is the others may be like I said one depends on adjustment of the ones before them. At least rule that out spin by hand now you see one slip - engine off of course,

[Cornbinder89]

IIRC these use a resistor pack for the slower speeds and a high blower relay for the fastest. It sounds like someone bypassed it all and ran power direct to the blower.

[Tom Greenleaf]

A good maybe CB89. jfkelly: You said it also blows cold? Is that to say it wasn't blowing cold at lower blower speed? Low speed otherwise would blow colder just less of it.
More thought on belts or plain voltage by revving up engine if so - still a guess. It starts so alternator is doing something OK but supposed to stay up over 13V when running. Motors do slow down if say it's at 10-11V noticeable. That's also lost for a magnetic clutch to stay and not slip?

Running out of time for a hot weekend to check voltage with any fool meter at the battery as this runs. Battery could be weak but not if it started would still spike up. See what it reads at posts - the bolt not the eyelet is not true battery but note both.

If low but better than when off - totally off that is, keys out alt works just a diode quit 3 come as one inside alternator. Most still run just low. Other vehicles would give you a battery light or some still call it a GEN read box light this shouldn't have that.

If so and you are handy can take that alternator apart and do just those. Index it and hold brushes back with like paper clip wire it comes apart. Diode trio just screws in but if brushes worn toss it for a rebuilt or check first if there's any savings IDK what's available to you for heading into a weekend?

If you go there of course disconnect neg battery post while working you lose the radio presets and a clock if that still works nothing else. All that just for a way out if only that problem actually was common to me assorted GMs cars or trucks!